Macaulay Culkin was born and raised in Manhattan, New York.
Culkin was brought up a Catholic and attended Catholic school for 5 years before his career got in the way of his studies. Furthermore, his father's job while Culkin was growing up was to prepare the church for Mass, a duty with the title of sacristan.
So, we can be sure that Culkin's religious played an important role during his formative years.
But we're unsure of Culkin's current level of devotion to Catholicism–or any religion for that matter. He is notoriously private about his views in that regard. We know that he has read the Bible at least once and he seems to feel that religion in general (though Christianity specifically), at its foundation, offers a positive message. He said:
The basis of any religion, let alone anything Christ-related, is be a good person, be good to the people around you and accept them for who they are. And that's it, whether you're a Buddhist or anything like that, that's the message.
As far as classification, he seems Catholic by heritage and most likely non-religious in practice.
Drugs and politics can mix
Culkin is again rather private about his political views. Maybe he doesn't even have any. It's possible that Culkin is so set up, he doesn't have to care about anything. He did once say:
I could sit around with my thumb up my butt watching TV and my kids would still go to college!
He's been the mud in a political mudslinging campaign, though. Apparently, as rumors were flying that Culkin was a heroin addict, a pro-Democrat Super-PAC accused Mitt Romney of being Culkin's heroin dealer. Spokesperson for the PAC, Bill Burton, went on a nationally televised political commentary show with CNN anchor Wolf Blitzer and said:
The Obama campaign has recently unearthed documents that will lend credence to the National Inquirer's story that Macaulay Culkin has six months to live due to struggles with a heroin addiction. Unfortunately, the evidence all points to Gov. Mitt Romney. It turns out that Mitt Romney has been Culkin's dealer for years.
This wasn't just some crazy off the street, but a powerful, legitimate political organization called Priorities USA. The allegations have yet to be proven true or false, but it seems rather far-fetched that a multi-millionaire and presidential candidate would have any good reason to sell heroin–to child stars or anyone else.