Jeremiah 20:14
Jeremiah 20:1414Cursed be the day I was born! May the day my mother bore me never be blessed.
Read as a passing expression of the prophet's grief and never engaged with at the level of what it implies about the day of one's birth. The Watchtower treats the verse as evidence of suffering, not as data about whether birth-days were customarily marked among the Israelites.
A prophet cannot wish a day "unblessed" unless blessing it was the custom. The Jewish Encyclopedia (1906) — not a Christian apologetic source — reads as implying that the day of birth had a recognised place among the Israelites. Pair the verse with ("Job opened his mouth and cursed the day of his birth") and ("many will rejoice at his birth"). The Bible's own pattern is that birth is a day to be marked. Two pagan tyrants mark it badly — Pharaoh and Herod — and the Watchtower generalises a sample of two into a prohibition. in the JW's own NWT settles the question of Christian liberty: "the one who observes the day observes it to Jehovah."