Yep, they are setting themselves up for difficulty down the road, especially if they are going to insist on challenging the beliefs of others. I grew up in the Evangelical tradition, but I was a Christian insomuch if a cow was in a tree, it'd be a bird. (In other words, I wasn't a fanatic.) Late in my teenage years, I started noticing that none of these denominations agreed on everything and that was a dealbreaker for me. I would spend the next 30 years as an agnostic. I only became a Christian when I challenged myself to try and figure it all out. (Coming face to face with my own mortality after several heart procedures had a lot to do with that, too.)