45 He, on hearing the salutation addressed to Elisabeth, leaped with joy in his mother's womb, recognising God the Word conceived in the womb of the Virgin. Thereafter he came forward preaching in the wilderness, proclaiming the baptism of repentance to the people, (and thus) announcing prophetically salvation to the nations living in the wilderness of the world. After this, at the Jordan, seeing the Saviour with his own eye, he points Him out, and says, “Behold the Lamb of God, that takes away the sin of the world!” He also first preached to those in Hades, becoming a forerunner there when he was put to death by Herod, that there too he might intimate that the Saviour would descend to ransom the souls of the saints from the hand of death.
Source: The Antichrist (New Advent)