The question your wife asks is really, “what is faith?” because faith is required for repentance.
When the Church responds to the call: Repent and be baptized, she does it for the whole Church. Faith does not exist in a vacuum, nor is it limited to personal, individual belief – especially in the context of family life.
When we baptize infants, we baptize them into grace for the remission of original sin. Faith and repentance go hand-in-hand throughout one’s life at every level of cognizance and understanding.
Peter says: “Repent, and be baptized every one of you in the name of Jesus Christ for the forgiveness of your sins; and you shall receive the gift of the Holy Spirit. For the promise is to you and to your children and to all that are far off, every one whom the Lord our God calls to him.” (Acts 2:39-39)
Moreover, in Luke 5:18-20 we see Jesus offering forgiveness to the paralytic not because of his faith or because of his own repentance, but because of the faith of those who brought him to Jesus:
And behold, men were bringing on a bed a man who was paralyzed, and they sought to bring him in and lay him before Jesus; but finding no way to bring him in, because of the crowd, they went up on the roof and let him down with his bed through the tiles into the midst before Jesus. And when he saw their faith he said, “Man, your sins are forgiven you.”
Furthermore, faith needn’t be mature. In Luke 41-44, when Mary, pregnant with the Lord, entered the house of Zechariah and Elizabeth
"the babe leaped in her womb; and Elizabeth was filled with the Holy Spirit and she exclaimed with a loud cry, "Blessed are you among women, and blessed is the fruit of your womb! . . .
For behold, when the voice of your greeting came to my ears, the babe in my womb leaped for joy.
Even without full, rational faith, which would be required for full rational repentance, the babe “leaped for joy.” – That’s faith!