In one sense, it is imperative that I do choose for him, because the choice has already been made. There are many things that we do not get to choose when we are born, such as parentage, and family. Just as Christopher has earthly parents, grandparents, aunts and uncles, he has a Heavenly Father, and just as it is our responsibility to bring him early into relationship with his earthly parents and other family members, it is our responsibility to enable his relationship with God. And this relationship with God, we believe as Christians, comes through Jesus. It is therefore essential that we not only encourage an amorphous relationship with God, but teach him the specific ways in which this relationship is maintained and deepened through Christ - by his teaching, and by belonging to his Body, the Church. So through baptism he is born into the body of Christ, through prayer he learns the words to begin a conversation with Christ, and through the sign of the cross he learns the shape of the way to God.
In another sense, however, it's clear that I cannot choose anything for Christopher. No matter what I teach him, he has his own free will to exercise, and he can choose to accept or reject the relationship with God into which he has been born, just as he will someday choose his own response to other relationships into which he was born.