Depend how religious he becomes; if it's really average joe religion, than I really won't care, I'll even find it good since it will make Christmas and Al Aid dinners much more interesting with all the debate about God.
If however, he/she become a fundamuntalist nut (the kind that advocates killing people he doesn't "agree" with like gays) than I really will be disappointed, I don't see myself abondening m kid though