Been hearing this for years and have only lately learned that it isn't true. The celebration of Christ's birth, it turns out, harkens back to a desire to celebrate Christs’ birth. The date decided upon was fixed by the belief that Christ died on the same date that He was born with Christmas being the date of the Immaculate Conception.
Oops! CONCIEVED and died on the same day with Christmas as the birth.
Try googling “winter solstice”
It’s pretty easy to work out that Christ was born at Tabernacles from the priestly course of John’s father, Zechariah.