The fact that our Lord Jesus Christ praised St. John the Baptist so highly, saying that among those born of women there was none greater, encouraged a special veneration, and so we find a regular cycle of feasts in his honour among the early Christian churches.
It was the firm belief among the faithful from the time of the early Church that John was freed from original sin at the moment of the meeting of his mother with the Blessed Virgin, when the child "leaped in the womb" of St. Elizabeth. Saint Augustine mentioned this belief as a general tradition in the ancient Church, establishing that he was "filled with the Holy Spirit even from his mother's womb" and, therefore, was born without original sin. Accordingly, the Church celebrates his natural birth by a festival of his nativity, assigned some six months before the nativity of Christ, since John was six months older than the Lord.
Almighty God, by whose providence thy servant Saint John the Baptist was wonderfully born, and sent to prepare the way of thy Son our Saviour, by preaching of repentance: make us so to follow his doctrine and holy life, that we may truly repent according to his preaching; and after his example constantly speak the truth, boldly rebuke vice, and patiently suffer for the truth’s sake; through the same Jesus Christ thy Son our Lord, who liveth and reigneth with thee, in the unity of the Holy Spirit, ever one God, world without end. Amen.