This is a political move. Outside of Madison, considered the only liberal city in the state, Wisconsin is still a very conservative catholic state. Just like most of the older presidents used to do, playing the Christianity card, he's trying to appeal to a majority.
Geez, it must run in the Repub party...now that it's campaign season, we learn Newt Gingrich also has a "personal" relationship with god, having had 3 wives is just a minor issue...and who can forget GWB telling a Palestinian official, "God told me to invade Iraq"?