Please note that previously Christ's age at death was cited as 33 years and 7 months: it should reflect 33 years and 6 months— please forgive the typo. This response also addresses recent Bible scholar declarations that Christ was born September 29th, 5 B.C: proving Biblically that such a date is full of holes.

Nevertheless, the short answer to Alfred's question: According to Luke 2:8-9, the shepherds were in the field watching over their flocks, at night. The "angel of the Lord," who is Gabriel— the only angel referred to as an "angel of the Lord" and who periodically gives his name— came to announce Christ's birth to them. 

This was sometime during October, based on Luke 1:26— which reveals Mary's impregnation to have occurred in the Hebrew sixth month, Adar, the same as our Gregorian February, of 4BC. Allowing for a normal and healthy period of gestation days, Jesus then had to have been born sometime in the Hebrew second month, Cheshvan, which would be October of 3BC. 

Additionally, Gabriel informed Mary, in Luke 1:35, that the Holy Ghost would come upon her. Previous TSaS responses scripturally proved that Gabriel is the Holy Ghost: it is one of his titles/duties. Therefore, Gabriel came upon her in the sixth month, Adar or February. Between Mary and Elizabeth, sixth month and six months are used repeatedly. This is Biblically clarified without flaw hereinbelow.

Papal Rome arbitrarily set December 25^th as a day to celebrate our Lord and Saviour's birth, which quickly was adopted by all Protestant denominations: the Papacy having cited, as a justifying excuse, that no one knew when Christ was born. When this failed to hold up to original theological studies, Christianity's reason then was amended to it being a way to save idolatrous heathens. Amazing! Jesus nor His Apostles or disciples did or participated in any pagan things to save us Gentiles: absolutely nothing having anything to do with pagan idolatry. 

Still, for over a thousand years, theologians continued to state that Christ was born sometime in October of 3BC: which concurs with over 30 years of research I've conducted; more remarkable being the fact I didn't know theologians agreed with my findings until about three years ago. 

More recently, however, so-called Bible scholars are saying He was born on or about, their "best guess," September 29 of 5BC: which would mean:
1) Mary delivered prematurely by over 4 weeks;
2) Jesus would have been 29 when He started His ministry; and,
3) He would have been 32-1/2 when he died in 31AD. 

Yet, Luke and documented history clearly states:
1) Mary did not experience a premature birth, she completed her term;
2) Jesus was 30 when He began His ministry, according to Luke 3:23; which ministry continued for 3-1/2 years, making him 33-1/2 at His crucifixion; and,
3) historical records testify that Christ died in 31AD at the age of 33 years and 6 months; which also testifies to Jesus having been born in October of 3BC. 

Therefore, neither the month of September nor the year 5BC holds up to spiritual scrutiny. Neither does September 29^th bear up to God's Word: it is as stated, a best guess. While there is much scripture to validate an October 3BC birth, the Bible utterly is silent concerning the specific day. This is logical in that not one ancient prophecy concerning a promised Messiah revealed the day or hour of His birth: in due time, however, those portents did reveal the year. By the same token, not one prophecy relative to Christ's return, to take us up, provides the day or hour of this long awaited event. 

In these two momentous events, predetermined in humanity's course, prophecy provided only sufficient evidence to determine the year and season— in due time— but not the day or hour: just as Jesus said, "No man knows the day or hour except the Father." Thus, He was born "like a thief" and will return "like a thief." Therefore, it concludes that we may look for His return sometime during harvest season at the close of 6000 years, which could well expire sometime during harvest season 2004: any day, any hour now. 

The hypothesis of September is loosely based on the shepherds still being in the fields tending their flocks as well as Rome having sent out a degree for census taking— its citizens having to register as such— without any regard to Luke 2:3,6-AKJV clearly stating that it was not for census registration but for taxation, during which time Luke reveals Mary's term was "accomplished," as it were: completed. 

There is nothing here to suggest that Mary did not carry our Saviour to full term: which a September date would mean a premature birth by more than 4 weeks. Medically, it has been proven that a baby delivered at 8 months of gestation has a lesser chance of survival than a baby born in the 7^th month. Still, there is no reason to believe an early birth. 

Additionally, September would not be the last month shepherds would have been in the fields: then or now. There still would be a month of harvest to go and the weather still is warm in October around Bethlehem. Therefore, the fact that shepherds were in the fields does support October as the month of birth: as opposed to either December or September.

And finally, taxation would not be done until harvest was near completion: otherwise, Rome would have shortchanged itself. It is highly unlikely that greedy Rome would have shortchanged itself by taxing the people before all of their harvest was accounted for. Does the USA government? No way. Uncle Sam wants taxes based on our income from the first day of the year right through the last day. Rome was no dummy: after all, they were the longest ruling world power ever in existence. Nonetheless, Joseph was a carpenter, so it would not be surprising that he would go to Bethlehem in October, as opposed to the end of harvest thus November: not being hampered with a final harvest.

* * * * * Luke 1:26-27,30-31,35-37, 38-42—And in the sixth month [ADAR, February] the angel Gabriel was sent from God unto a city of Galilee, named Nazareth, to a virgin espoused [betrothed, engaged] to a man whose name was Joseph, of the house of David; and the virgin's name was Mary. And the angel said unto her, Fear not, Mary: for thou hast found favour with God. And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS. 

And the angel answered and said unto her, The Holy Ghost [who is Gabriel] shall come upon thee, and the power of the Highest shall overshadow thee: therefore also that holy thing which shall be born of thee shall be called the Son of God. And, behold, thy cousin Elisabeth, she hath also conceived a son in her old age: and this is the sixth month with her, who was called barren. For with God nothing shall be impossible.

And Mary said, Behold the handmaid of the Lord; be it unto me according to thy word. And the angel departed from her. And Mary arose in those days, and went into the hill country with haste, into a city of Juda; and entered into the house of Zacharias, and saluted Elisabeth. And it came to pass, that, when Elisabeth heard the salutation of Mary, the babe leaped in her womb; and Elisabeth was fill with the Holy Ghost: and she spake out with a loud voice, and said, Blessed art thou among women, and blessed is the fruit of thy womb. * * * *  

Luke conveys that Mary conceived Jesus in the sixth month (Adar) of the Jewish calendar, which translates as February. Luke 1:36,40-42 further clarifies that, indeed, Mary conceived in the sixth month: validated by Elizabeth, who had conceived John the Baptist in September of 4BC, Christ's cousin, six months prior to Christ's conception and whom Mary visited when Elizabeth already was six months along: as Gabriel had informed Mary. Luke further enlightens of Mary’s pregnancy having extended full-term, placing Christ’s birth around early to even late (Cheshvan of the Jewish calendar) October of the Gregorian calendar. 

The first year of AD was intended to be the year of Christ’s birth but, due to error in calculating the then new calendars— failure to consider Christ's age at death and backtracking accordingly— the calendar creators missed it by 2-1/2 to 3 years: a fact heavily documented historically. This is validated by the year of king Herod's death, at which time Joseph returned his family from hiding in Egypt: Christ was nine years old at that time. 

Three years later, at the age of 12, Christ was found preaching in the Temple following the Passover festival held on March 30^th and April 1^st of 9AD. He was not seen or heard from again until He began his ministry in October of 27AD, at which time Luke declared Jesus to be 30 years old. Then, three years and six months later, when Jesus was 33 and 6 months of age, He was crucified: April 03, 31AD, thus it computes without flaw to place His birth sometime in October in the year of 3BC (calendar matching provided hereinbelow). 

In re-evaluating all these dates, it would be more logical to determine the day of His birth as having been October 03, 3BC— exactly 33-1/2 years prior to His death on April 03, 31AD. Nevertheless, the Bible does not provide sufficient data to establish an exact day. 

Luke 2:1-5 additionally chronicles that Rome's tax assessment was what prompted Joseph to take his pregnant wife to Bethlehem: further confirming an October birth inasmuch as tax collection logically followed the close of harvest season— the first such Roman taxation having begun the year Christ was born: according to Luke. Census, however, had been going on for a long time before Jesus even was born. 

October is the third and last month of harvest season as well as the second month of the Hebrew year. Additionally, all major Biblical events, including redemption, refer strongly to harvest time. Add the fact shepherds still were in the fields with their flocks when Gabriel appeared to them. This too would be normal since October is autumn in Israel (not winter, December [Tebet] or January [Shebat]). History reveals that their sheep would not have been in the fields during winter but definitely would have in October. 

NOTE: Biblically, a new day begins at sundown and ends with the next sunset: contrary to Papal Rome having established a day as being from midnight to midnight. All dates rendered in the RESULTS, following the calendar comparisons below, are based on what God discerns as a 24-hour day: night being the first 12 hours and the next daylight being the final 12 hours. 

Now compare the two calendars set out below: World Book Encyclopedia, confirms Jewish names of months as exactly those used in the Authorized King James Bible. Any other month names used would have to have been bastardized, thus should not be applied for the purpose of gaining a spiritual rendering.

GREGORIAN                         HEBREW

1.  January (31 days)           1.  September (Tishri, 30 days) 
     New Year, 1^st                       New year, 11^th 
                                                   Day of Atonement, 20^th 
                                                   Feast of Tabernacles 15-20^th
                                                   Rejoice in the Law, 23^rd

2.  February (28-29 days)     2.  October (Cheshvan, 29-30 days)
     St. Valentines, 14^th                                                

3.  March (31 days)              3.  November (Kislev, 29-30 days)
     St. Patrick’s Day, 17^th            Feast of Dedication, 25^th
     Palm Sunday, 28^th

4.  April (30 days)                4.  December (Tebet, 29 days)
     Good Friday, 2^nd                    Festival of Lights, 2^nd 
     Easter, 4^th in 1999

5.  May (31 days)                5.  January (Shebat, 30 days)

6.  June (30 days)                6.  February (Adar, 29-30 days) 
                                                  Feast of Lots, 14^th

7.  July (31 days)                 7.  March (Nisan, 30 days) 
                                                   Passover, 30^th

8.  August (31 days)             8.  April (Iyar, 29 days) 
                                                   Passover, 1^st

9.  September (30 days)       9.  May (Sivan, 30 days) 
                                                   Feast of weeks, 5^th

10. October (31 days)        10.  June (Tammuz, 29 days) 
       Halloween, 31^st

11. November (30 days)     11.  July (Ab, 30 days) 
       Thanksgiving, 25^th                Day of Fasting, 9^th

12. December (31 days)      12.  August (Elul, 29 days) 
       Christmas, 25^th

RESULTS: 

1) Mary conceived Jesus sometime in February 4BC; Luke 1:26,36,40-42
2) Jesus was born early to late October 3BC (based on typical number of gestation days and determined by exact February day of conception) in Bethlehem; Luke 2:1-6,8,11
3) Christ began His ministry on His 30^th birthday, or October 27AD; Luke 3:23
4) Jesus was arrested on the morning of Thursday April 2^nd, the day after conclusion of Passover festival, and was crucified on Friday morning, April 3^rd, 31AD, pronounced dead at approximately 3PM at the age of 33 years and 6 months; Luke 23:44-46
5) At sunset, now April 4^th, 31AD Jesus was placed in a tomb where He remained through Saturday Sabbath sunset, now April 5^th, 31AD; Luke 24:55-56
6) At dawn on Sunday, April 5^th, 31AD Christ arose from His grave and was seen by many people for 40 days; Luke 24:1-3; Acts 1:3
7) On the 40^th day, Thursday, about May 14^th or 15^th of 31AD Jesus ascended to heaven, obscured by a cloud. Luke 24:51; Acts 1:9

Since the whole Bible is about God, the Hebrews— Judah and Israel— Christ, and adopted Hebrews— pagan Gentiles—­ then it is most appropriate to discern these dates in accordance with ancient Hebrew calendars. After all, that is the time in which these records were written and events occurred. Biblically, there would have been no other calendar. Realistically? Yes, there were pagan calendars even then, but to use one of those would be to discern God's Word by the world: instead of spiritually. 

Note: Hebrew calendars still are in use today among Orthodox and Christian Jews observing ancient Jewish festivals. It remains the same as it was from the beginning of Creation. Therefore, the Hebrew September is the same September we recognize. It just happens to be the Jews' first month of the year, whereas a Gregorian calendar begins the year with January. 

World Book Encyclopedia: Bethlehem is located in the hilly or mountainous region of Israel. In winter months, beginning in December, temperatures can drop as low as 42 degrees at night. This is not so for previous months, especially concerning October, which remains very warm. 

Also, the Gospels do not indicate freezing winter with snow on the ground at Christ's birth—a familiar Christmas scene with which we've all grown up. If it had been winter, the shepherds would not have been in the fields. After all, there would have been nothing in the fields for the sheep to eat. 

All these little subtleties grouped together cause the world to believe lies and walk after Satan unaware, guilty by virtue of not checking out every last one of God's facts for self.