This is a detailed study of the dates. Portions taken from Appendix 179 of the Companion Bible.
May they give you a better understanding and also help others. Sometimes "traditions of men" are off about 180 degrees. Some of this is the work of the Devil, to keep us from knowing the truth so we you won't be prepared for upcoming events. He, i.e. Satan is the great imitator. When he gets kicked out of heaven by Michael in the future, he (Satan = Antichrist = in stead of Christ) will be pretending he is Jesus, so be careful who you listen to. When I tell people of these truths, I try to do it in a loving way so as to not rock the boat and offend people, but to let them know that things may not always be as they seem. The TRUTH will set us free.
1. It thus appears without the shadow of a doubt that the day assigned the the Birth of the Lord, viz. December 25, was the day on which He was "begotten of the Holy Spirit", i.e. by pneuma hagion = divine power (Matt. 1:18, 20 marg.), and His birth took place on the 15th of Ethanim, September 29, in the year following, thus making beautifully clear the meaning of John 1:14, "The Word became flesh" (Matt. 1:18, 20) on the 1st Tebeth or December 25 (5 B.C.), "and tabernacled (Gr. eskeno-sen) with us", on 15th of Ethanim or September 29 (4 B.C.).
  The 15th of Ethanim (or Tisri) was the first day of the Feast of Tabernacles. The circumcision therefore took place on the eighth day of the Feast = 22nd Ethanim = October 6-7 (Lev. 23:33-34). So that these two momentous events fall into their proper place and order, and the real reason is made clear why the 25th of December is associated with our Lord and was set apart by the Apostolic Church to commemorate the stupendous event of the "Word becoming flesh" - and not, as we have for so long been led to suppose, the commemoration of a pagan festival.
2. An overwhelmingly strong argument in favor of the correctness of this view lies in the fact that the date of "the Festival of Michael and All Angels" has been from very early times the 29th day of September, on Gentile (Western) reckoning.
  But "the Church" even then had lost sight of the reason why this date rather than any other in the Calendar should be so indissolubly associated with the great Angelic Festival.
  The following expresses the almost universal knowledge or rather want of knowledge of "Christendom" on the subject: "We pass on now to consider, in the third place, the commemoration of September 29, the festival of Michaelmas, par excellence. It does not appear at all certain what was the original special idea of the commemoration of this day" (Smith's Dict. of Chr. Antiqq. (1893), vol. ii, p. 1177 (3) ).
  A reference, however, to the Table and statements above, makes the "original special idea " why the Festival of "Michael and All Angels" is held on September 29 abundantly clear. Our Lord was born on that day, the first day of the "Feast of Tabernacles" (Lev. 23:39). This was on the fifteenth day of the seventh Jewish month called Tisri, or Ethanim (Ap. 51. 5), corresponding to our September 29 (of the year 4 B.C.)
  The "Begetting" (genesis) Day of the Lord was announced by the Angel Gabriel. See notes on Dan. 8:16 and Luke 1:19.
  The "Birth" Day, by "(the) Angel of the Lord", unnamed in either Matthew and Luke.
  That this Angelic Being was "Michael the Archangel (of Jude 9), and Mika'el hassar haggadol - "Michael the Great Prince"- of Dan. 12:1, seems clear for the following reason: If, "when again (yet future) He brings the First-begotten into the world, He saith, Let all the Angels of God worship Him" (Heb 1:6; quoting Ps. 97:6) - then this must include the great Archangel Michael himself. By parity of reasoning, on the First "bringing" into the world of the only begotten Son, the Archangel must have been present. And the tremendous announcement to the shepherds, that the Prince of Peace (Isa. 9:6) was on earth in the person of the Babe of Bethlehem, must therefore have been made by the same head of the heavenly host (Luke 2:9-14). In mundane affairs, announcements of supremest importance (of kings, &c.) are invariably conveyed through the most exalted personage in the realm. The point need not be labored.
3. The fact of the Birth of our Lord having been revealed to the shepherds by the Archangel Michael on the 15th of Tisri (or Ethanim), corresponding to September 29, 4 B.C. - the first day of the Feast of Tabernacles - must have been known to believers in the Apostolic Age. But "the mystery of iniquity" which was "already working" in Paul's day (2Thess. 2:7) quickly enshrouded this and the other great fact of the day of the Lord's "begetting" on the first day of the Jewish month Tebeth (corresponding to December 25, 5 B.C.) - as well as other events connected with His sojourn on earth, (*1) - in a rising mist of obscurity in which they have ever since been lost.
  The earliest allusion to December 25 (modern reckoning) as the date for the Nativity is found in the Stromata of Clement of Alexandria, about the beginning of the third century A.D. (*2)
  That "Christmas" was a pagan festival long before the time of our Lord is beyond doubt. In Egypt Horus (or Harpocrates (*3), the son of Isis (Queen of Heaven), was born about the time of winter solstice. (*4) By the time of the early part of the fourth century A.D., the real reason for observing Christmas as the date for the miraculous "begetting" of Matt. 1:18 and "the Word becoming flesh" of John 1:14 had been lost sight of. The policy of Constantine, and his Edict of Milan, by establishing universal freedom of religion furthered this. When many of the followers of the old pagan systems - the vast majority of the empire, it must be remembered - adopted the Christian religion as a cult, which Constantine had made fashionable, and the "Church" became the Church of the Roman Empire, they brought in with them, among a number of other things emanating from Egypt and Babylon, the various Festival Days of the old "religions" (Including "Easter" which is a pagan festival in which orgies took place. We are suppose to celebrate "Passover". Christ is our Passover. Father hates bringing in traditions of men into His House. It's ok to go out into the world, but DO NOT bring the heathenistic practices of the world into His House. That is an abomination). Thus "Christmas Day, " the birthday of the Egyptian Horus (Osiris), became gradually substituted for the real Natalis Domini of our blessed Savior, viz. September 29, or Michaelmas Day.
4. If however, we realize that the center of gravity, so to speak, of what we call the Incarnation if the Incarnation itself- the wondrous fact of the Divine "begetting", when "the Word became flesh" (see notes on Matt. 1:18 and John 1:14) - and that this is to be associated with December 25, instead of March - as for 1,600 years Christendom has been led to believe - then, "Christmas" will be seen in quite another light, and many who have hitherto been troubled with scruples concerning the day being, as they have been taught, the anniversary of a Pagan festival, will be enabled to worship on that Day without alloy of doubt, as the time when the stupendous miracle which is the foundation stone of the Christian faith, came to pass.
  The "Annunciation" by the Angel Gabriel marked the genesis of Matt. 1:18, and the first words of John 1:14.
  The announcement to the shepherds by the Archangel Michael marked the Birth of our Lord. John 1:14 is read as though "the Word became flesh (R.V.) and dwelt among us ", were one and the same thing, whereas they are two clauses.
  The paragraph should read thus:
    "And the Word became flesh;
        (Gr. ho logos sarz egeneto.)
    And tabernacled with (or among) us."
        (Gr. kai eskenosen en hemin).
  The word tabernacled here (preserved in R.V. marg.) receives beautiful significance from the knowledge that "the Lord of glory" was "found in fashion as a man", and thus tabernacling in human flesh. And in turn it shows in equally beautiful significance that our Lord was born on the first day of the great Jewish Feast of Tabernacles, viz. the 15th of Tisri, corresponding to September 29, 4 B.C. (modern reckoning).
  The Circumcision of our Lord took place therefore on the eighth day, the last day of the Feast, the "Great Day of the Feast" of John 7.37 ("Tabernacles" had eight days. The Feast of Unleavened Bread had seven days and Pentecost one. See Lev. 23)
5. The main arguments against the Nativity having taken place in December may be set forth very simply:
    (i) The extreme improbability, amounting almost to impossibility, that Mary, under such circumstances, could have undertaken a journey of about 70 miles (as the crow flies), through a hill district averaging some 3,000 feet above sea-level, in the depth of winter:
    (ii) Shepherds and their flocks would not be found "abiding" (Gr. agrauleo) in the open fields at night in December (Tebeth), for the paramount reason that there would be no pasturage at that time. It was the custom then (as now) to withdraw the flocks during the month Marchesvan (Oct.-Nov.) (**1) from the open districts and house them for the winter.
    (iii) The Roman authorities in imposing such a "census taking" for the hated and unpopular "foreign" tax would not have enforced the imperial decree (Luke 2:1) at the most inconvenient and inclement season of the year, by compelling the people to enroll themselves at their respective "cities" in December. In such a case they would naturally choose the "line" of least resistance" and select a time of year that would cause least friction, and interference with the habits and pursuits of the Jewish people. This would be in the autumn, when the agricultural round of the year was complete, and the people generally more or less at liberty to take advantage, as we know many did, of the opportunity of "going up" to Jerusalem for the "Feast of Tabernacles" (cp. John 7:8-10, &c), the crowning Feast of the Jewish year.
  To take advantage of such a time would be to the Romans the simplest and most natural policy, whereas to attempt to enforce the Edict of Registration for the purpose of Imperial taxation in the depth of winter,- when traveling for such a purpose would have been deeply resented, and perhaps have brought about a revolt,- would never have been attempted by such an astute ruler as Augustus.
6. With regard to the other two "Quarter Days", June 24, March 25, these are both associated with the miraculous (Luke 1:7) "conception" and birth of the Forerunner, as December 25 and September 29 are with our Lord's miraculous "Begetting" and Birth; and are therefore connected with "the Course of Abiah."
  This was the eighth of the priestly courses of ministration in the Temple (I Chron. 24:10), and occurred, as did the others, twice in the year.
  The "Courses" were changed every week, beginning each with a Sabbath. The reckoning commenced on the 22nd day of Tisri or Ethanim (Ap. 51. 5). This was the eighth and last day of the Feast of Tabernacles = the "Great Day of the Feast" (John 7:37), and was a Sabbath (Lev. 23:39)
  The first course fell by lot to Jehoiarib, and the eighth to Abia or Abijah (1Chron. 24:10).
  Bearing in mind that all the courses served together at the three Great Feasts, the dates for the two yearly "ministrations" of Abiah will be seen to fall as follows:
    The first (*1) ministration was from 12 - 18 Chisleu = December 6 - 12.
    The second ministration was from 12 -18 Sivan = June 13 - 19.
  The announcement therefore to Zacharias in the Temple as to the conception of John the Baptist took place between 12 - 18 SIVAN (June 13 -19), in the year 5 B.C. After finishing his "ministration", the aged priest "departed to his own house" (Luke 1:23) which was in a city (*2) in "the hill country" of Juda (verse 39).
  The day following the end of the "Course of Abia" being a Sabbath (Sivan 19), he would not be able to leave Jerusalem before the 20th.
  The thirty miles journey would probably occupy, for an old man, a couple of days at least. He would therefore arrive at his house on the 21st or 22nd. This leaves ample time for the miraculous "conception" of Elizabeth to take place on or about the 23rd of Sivan (*3) - which would correspond to June 23 -24 of that year. The fact of the conception and it's date would necessarily be known at the time and afterwards, and hence the 23rd of SIVAN would henceforth be associated with the conception of John the Baptist as the 1st of TEBETH would be with that of our Lord.
  But the same influences that speedily obscured and presently obliterated the real dates of our Lord's "Begetting" and Birth, were also at work with regard to those of the Forerunner, and with the same results. As soon as the true Birth day of Christ had been shifted from its proper date, viz. the 15th of Tisri (September 29), and a Festival Day from the Pagan Calendars substituted for it (viz. December 25), then everything else had to be altered too.
  Hence "Lady Day" in association with March 25 (new style) became necessarily connected with the Annunciation. And June 24 made its appearance as it still is in our Calendar, as the date of "the Nativity of John the Baptist", instead of , as it really is, the date of his miraculous conception.
  The Four "Quarter Days" may therefore be set forth thus: first in the chronological order of the events with which they are associated, viz.:
The conception of John Baptist on or about 23rd Sivan = June 24 in the year 5 B.C.
The Genesis (Begetting of our Lord) on or about 1st Tebeth = December 25 in the year 5 B.C.
The birth of John Baptist on or about 4-7th Nisan = March 25-28th in the year 4 B.C.
The Birth of our Lord on or about 15th Tisri = September 29th in the year 4 B.C.
  or, placing the two sets together naturally:
The conception of John23 Sivan = June 23-24, 5B.C.
The birth of John 7th Nisan = March 28-29, 4 B.C.
The Miraculous "Begetting" 1 Tebeth = December 25, 5 B.C.
The Nativity 15th Tisri = September 29, 4 B.C.
78 | 78 156|156 234|234 Dec. TEBETH > 1=25-26 (5 B.C.) 20=12-13 10=29-30 29=15-16 (29) 2=26-27 21=13-14 11=30-31 30=16-17 3=27-28 22=14-15 12=31-1 ELUL > 1=17-18 4=28-29 23=15-16 13=1-2 < June (29) 2=18-19 5=29-30 24=16-17 14=2-3 (30) 3=19-20 6=30-31 25=17-18 15=3-4 4=20-21 7=31-1 26=18-19 16=4-5 5=21-22 8=1-2 < Jan. 27=19-20 17=5-6 6=22-23 9=2-3 (4 B.C.) 28=20-21 18=6-7 7=23-24 10=3-4 (31) 29=21-22 19=7-8 8=24-25 11=4-5 NISAN > 1=22-23 20=8-9 9=25-26 12=5-6 (30) 2=23-24 21=9-10 10=26-27 13=6-7 3=24-25 22=10-11 11=27-28 14=7-8 4=25-26 23=11-12 12=28-29 15=8-9 5=26-27 24=12-13 13=29-30 16=9-10 6=27-28 25=13-14 14=30-31 17=10-11 7=28-29 26=14-15 15=31-1 < Sept- 18=11-12 8=29-30 27=15-16 16=1-2 ember 19=12-13 9=30-31 28=16-17 17=2-3 (29) 20=13-14 10=31-1 < April 29=17-18 18=3-4 21=14-15 11=1-2 (30) 30=18-19 19=4-5 22=15-16 12=2-3 TAMUZ > 1=19-20 20=5-6 23=16-17 13=3-4 (29) 2=20-21 21=6-7 24=17-18 14=4-5 3=21-22 22=7-8 25=18-19 15=5-6 4=22-23 23=8-9 26=19-20 16=6-7 5=23-24 24=9-10 27=20-21 17=7-8 6=24-25 25=10-11 28=21-22 18=8-9 7=25-26 26=11-12 29=22-23 19=9-10 8=26-27 27=12-13 SEBAT > 1=23-24 20=10-11 9=27-28 28=13-14 (30) 2=24-25 21=11-12 10=28-29 29=14-15 3=25-26 22=12-13 11=29-30 ETHANIM (TISRI) > 1=15-16 4=26-27 23=13-14 12=30-1 (15) 2=16-17 5=27-28 24=14-15 13=1-2 < July 3=17-18 6=28-29 25=15-16 14=2-3 (31) 4=18-19 7=29-30 26=16-17 15=3-4 5=19-20 8=30-31 27=17-18 16=4-5 6=20-21 9=31-1 28=18-19 17=5-6 7=21-22 10=1-2 < February 29=19-20 18=6-7 8=22-23 11=2-3 (29) 30=20-21 19=7-8 9=23-24 12=3-4(Leap Year)ZIF > 1=21-22 20=8-9 10=24-25 13=4-5 (29) 2=22-23 21=9-10 11=25-26 14=5-6 3=23-24 22=10-11 12=26-27 15=6-7 4=24-25 23=11-12 13=27-28 16=7-8 5=25-26 24=12-13 14=28-29 17=8-9 6=26-27 25=13-14 ETHANIM or > 15=29-30 Sept- TISRI ember 18=9-10 7=27-28 26=14-15 Days on Jewish 280|280 Days on reckoning Gentile reckoning. 19=10-11 8=28-29 27=15-16 20=11-12 9=29-30 28=16-17 21=12-13 10=30-1 < May 29=17-18 (31) According to Jewish reckoning. 22=13-14 11=1-2 AB >1=18-19 TEBETH 29 days. 23=14-15 12=2-3 (30)2=19-20 SEBAT 30 24=15-16 13=3-4 3=20-21 ADAR 29 25=16-17 14=4-5 4=21-22 NISAN 30 26=17-18 15=5-6 5=22-23 ZIF 29 27=18-19 16=6-7 6=23-24 SIVAN 30 28=19-20 17=7-8 7=24-25 THAMMUZ 29 29=20-21 18=8-9 8=25-26 AB 30 30=21-22 19=9-10 9=26-27 ELUL 29 ADAR > 1=22-23 20=10-11 10=27-28 ETHANIM 15 (29) 2=23-24 21=11-12 11=28-29 280 3=24-25 22=12-13 12=29-30 4=25-26 23=13-14 13=30-31 5=26-27 24=14-15 14=31-1 According to Gentile (Western) reckoning. 6=27-28 25=15-16 15=1-2 < August December > 7 days. 7=28-29 26=16-17 16=2-3 (31) January 31 8=29-1 27=17-18 17=3-4 February 29 9=1-2 < March 28=18-19 18=4-5 March 31 10=2-3 (31) 29=19-20 19=5-6 April 30 11=3-4 SIVAN > 1=20-21 20=6-7 May 31 12=4-5 (30) 2=21-22 21=7-8 June 30 13=5-6 3=22-23 22=8-9 July 31 14=6-7 4=23-24 23=9-10 August 31 15=7-8 5=24-25 24=10-11 September 29 16=8-9 6=25-26 25=11-12 280 17=9-10 7=26-27 26=12-13 18=10-11 8=27-28 27=13-14 19=11-12 9=28-29 28=14-15280 days= 40 weeks--forty sevens, the perfect period of human gestation [7x5x8=280]. The Component Numbers of 280 are highly significant in this connection.
78 | 78 156 | 156 234|234
A.M. B.C.-A.D. A.C. A.U.C 3960 44 9 1 43 710 2 42 11 3 41 12 4 40 13 5 39 14 Herod declared king by the Romans, 6 38 15 his death took place thirty-seven 7 37 16 years later, and as he always 8 36 17 reckoned his years from Nisan to 9 35 18 Nisan, the death of Herod would be 3970 34 19 in 749-750 A.U.C., or 4-3 B.C.xxxx 1 33 720 Years of the Reign of Augustus 2 32 21 (Octavius). 3 Battle of Actium31 722 1st year of Octavius 4 30 Decree of Senate of Rome 23 2 5 29 24 3 6 28 25 4 Augustus (Octavia) 7 27 26 5 Imperator. 8 26 27 6 9 25 28 7 3980 24 29 8 1 23 30 9 2 22 31 10 3 21 32 11 4 20 33 12 5 19 34 13 6 18 35 14 7 17 36 15 8 16 37 16 9 15 38 17 3990 14 39 18 1 13 40 19 2 12 41 20 3 11 42 21 4 10 43 22 5 9 44 23 6 8 45 24 7 7 46 25 8 6 Years of the Age 47 26 9 5 of the Lord 48 27 4000 THE NATIVITY >4 0 749 Herod dc 28< our Lord b. 15th Tirsi 1 1st taxing of 3 Quirinus' 1 First 50< of Jan. 29 28th Sept. 4 B.C. 2 Census Luke 2:2 >2 2 Governorship 51 3 b.c. 30 3 1 3 52 31 4004 0 A.D. 4 753 32 < A.D. reckoning begins 5 1 5 54 33 owing to the mistake of 6 2 6 55 34 Dionysus Exiguus, in 7 3 7 56 35 arranging the Calendar 8 4 8 57 36 of the Christian Era 9 5 9 58 37 in 532 A.D. 4010 6 10 59 38 1 7 11 60 39 2 8 Christ in 12 the Temple 61 40 3 9 13 62 41 4 2nd Census (?)> 10 14 63 42 Years of the Reign 5 11 15 64 43 of Tiberius 6 12 16 65 1st year 44 Tiberius 1 joint reign 7 13 17 66 45 with 2 Augustus 8 14 18 67 19th > 46< Augustus 3< Tiberius 9 15 19 68 August dies 4 alone 4020 16 20 69 5 1 17 21 770 6 2 18 22 71 7 3 19 23 72 8 4 20 24 73 9 5 21 25 74 10 6 22 26 75 11 7 23 27 76 12 8 3rd Census (?)> 24 28 77 3rd Census 13 this year? 9 25 29 78 14 4030 The Ministry 26 of our 30 Lord 779 Begins (Luke 3:32)in 15th year of 1 27 31 780 16 Tiberius 2 28 32 81 17 4033 THE CRUCIFIXION 29 A.D. THE 33 YEARS OF 782 A.U.C. ROMAN THE 18TH " ANNO MUNDI LORD AGE RECKONING
1. ZUMPT fixes Quirinus' (Cyrenius') First Governorship as 4 B.C. to 1 B.C. Justin Martyr thrice says that our Lord was born under Quirinus (Apol.1.XXXIV, p.37; XLVI, p. 46; Dial. LXXVIII, p. 195. Clark's ed.).
2. According to some, Augustus died August 19, A.D. 14. Therefore if Tiberius' co-regnancy was for two years before Augustus' death his first year was 765 A.U.C. = 12 A.D. His fifteenth year consequently was A.U.C. 779 = 26 A.D. = 4030 A.M. and A.C. 30. for our Lord was thirty years of age when He begun His Ministry (Luke 3:23). Clement of Alexandria gives the years of Augustus' reign as being 43-46, according to different reckonings in his day.
3. According to Clement of Alexandria (c. A.D. 190-220) "Our Lord was born in the twenty-eighth year when first the census was taken every fourteen years, then the next would fall in A.D. 10, and the succeeding one would have been due A.D.24.