In general, I think that the core thrust of many Christian sects is the notion that they are the special, chosen group. This leads to in-group thinking, which in turn leads to feeling superior to other groups.
I am guessing you have never heard of Howard Conder then. Infact, according to the scripture the Jews
are God's people, and never haven't been. We are not a "chosen" group, God welcomes all, we may ALL be chosen but there is no barrier, Christ says he wishes no-one to perish, and anyone who comes to him will in no wise be cast out.
Another particularly troblesome part of Christianity is one that naturally grows out of this arrogance of considering itself the One True Religion
Again, this is certainly not the case among all christians. The Jewish people worship the same God.
Also, I have stated on this site that if Muslims worship God I do not necessarily see that as a bad thing. I think but I can't know for sure, that the Quran mentions the OT and NT, I've even heard it suggests following it. (Only heresay though).
So, we are obviously going to think our religion is true or we wouldn't follow it. Does this make us arrogant? - only as arrogant as the next religion!
The very most kind and wonderful people I have ever known, almost to a person, have been non-religious and/or athiest.
Hmmmm...