I once heard a priest preach that John the Baptist was born without original sin because he was baptized when he encountered Jesus in the womb at the time of Mary’s visit to Elizabeth. True or false?
There is indeed a pious Christian speculation that John the Baptist was freed from sin when he was filled with the Holy Spirit in his mother’s womb (cf. Luke 1:15, 41-44), but this is not something the Church has declared to be doctrine. The Church certainly has not taught that John the Baptist was baptized in his mother’s womb, if by that is meant the kind of baptism that babies receive after birth.