As someone who used to be religious and go to church, I'm going to have to disagree with some of the other people here. I don't think we can sit and judge a person’s sincerity or faith from the outside.
When I went to church, back when I really believed in it, I was not any better of a person than I am now. I sometimes made bad choices then, and to this day I still make bad choices from time to time. Religion doesn’t even have much to do with that- that’s just me… flawed and imperfect in character. I can only say that… every year I grow older, I’d like to think I’m moving forward and improving.
Maybe the biggest difference between then and now was that as a Christian I was more open to scrutiny and judgment, and more likely to be called a “hypocrite”. Every Christian, whether they like it or not, is treated like a representative for Christianity. Many people, without thinking things through, will take a Christian they meet at face value, and base their entire opinion of that religion off of their impression of that individual, positive or negative. (It’s kind of like the way the misinformed masses of America choose candidates during election time.)
The reason why this makes no sense is that Christians are struggling to be better people just like anyone else. Their faith isn’t a magic pill that can transform them into a saint overnight, but that doesn’t mean they aren’t trying. In fact the very idea behind a Christian’s faith is to *help* them because we all are so imperfect and because we all really have a long way to go in becoming the best versions of ourselves. People can sincerely regret things they’ve done, and sincerely have the desire and will to do better in the future… and still mess up again!! And people looking on the outside have no idea, and can’t begin to know what is going on inside of them, so it can be easy to just judge them and cast them off easily as hypocrites.
Now you may have some situations you can bring up that have to do with this or that specific individual who truly did something outrageous that would convince the average person that they use religion in a negative, harmful, and judgmental way toward others- but that’s them. The only point you will really be proving is that some of those specific individuals may have been hypocritical. That’s situational- and those individuals don’t represent all Christians.
I really don’t think it’s fair to assume that when you go to church that a lot of people are just going to “keep up appearances.” I’m willing to say maybe some people go for that reason, but as an ex-believer- who truly and sincerely believed, I really think they would only make up a very small percentage of adult church-goers.
Anyway, I just wanted to add my perspective on the matter. One of the things we should be able to pride ourselves in, as agnostics, I would think, is the fact that we are less prone to pass judgment on others. After all we’re the ones who are supposed to be the most honest with ourselves about how much we do *not* know

… and that includes the hearts and minds of others.