Regrettably, predominantly Democrat. Even many of the truly faithful.
Sure, if you hop back in a time machine and visit 1960. Here in the 21st century, Catholics are a swing vote that votes very closely to the country as a whole. "Catholic" John Kerry learned that the hard way when he lost the Catholic vote to George W. Bush in 2004. In 2008, the nation as a whole went heavily Dem, so did Catholics. In 2014, the nation as a whole went heavily GOP, so did Catholics. White, church-going Catholics have been abandoning the Dems in droves according to all the latest polling data.
Meanwhile, numerous FReepers seem to living in a parrell universal where the Jewish vote is "in play" (unlike here in the real world where they've vote overwhelming 70-80% Dem for decades and even Ronald Reagan himself couldn't get 40% of the Jewish vote in his 49-state landslide), but the Catholics are "totally owned by the Democrats" and not worth pursuing (unlike here in the real world where they vote equally for both parties)
Must be an interesting parallel universe you guys live in. If geographic regions worked like your view of religious groups, Ohio would be "totally Democrat controlled" and Maryland would be "in play" for the GOP presidential nominee to carry in November.