|ANSWER: St. John the Baptist was the baby!
St. John the Baptist would grow up to baptize people in the Jordan River as he prepared the world for the Messiah. Upon Mary’s arrival at Elizabeth’s house, Mary gave those famous words now known as the “Magnificat.” (Luke 1:46-55)
MAGNIFICATAnd Mary said, “My soul magnifies the Lord, and my spirit rejoices in God my Savior, for he has regarded the low estate of his handmaiden. For, behold, henceforth, all generations will call me blessed, for he who is mighty has done great things for me, and holy is his name. And his mercy is on those who fear him from generation to generation. He has shown strength with his arm, he has scattered the proud in the imagination of their hearts, he has put down the mighty from their thrones, and exalted those of low degree; he has filled the hungry with good things, and the rich he has sent empty away. He has sent his servant Israel, in remembrance of his mercy, as he spoke to our fathers, to Abraham and to his posterity for ever.” (CE-RSV)