As a Christian who leans more Quaker than anything else, I find the ritualism and ostentatious church buildings of most deniminations a bit repugnant. After that, it is the "holier than thou" attitude. I have heard it said that the biggest problems with Christianity is the Christians.
@jacobtothe Having traveled a decent amount, I have been able to see many temples and churches of different denominations around the world, and I must say, to your point, there is a consistent theme of opulence and hedonism throughout. These religious building do often make for a great picture though.
To your second point of the "holier than thou" attitude, I think it inevitably results from human nature. We instinctually either fear or discredit things that we do not understand. If this is what I believe in, then it must be the best and only thing to believe in, right?
All one need do is look to partisan politics where people condemn others as the embodiment of evil over purely secular disagreements, or the numerous variants of, "You were born on the other side of that national border, so you are less worthy of respect as an individual, and probably a criminal to boot!"