Religions don't cause problems. People cause problems. Most Abrahamic relgions (this includes Christianity and Islam) preach peace, fortitude under duress, and forgiveness. If the majority of people who are religious practiced those tenets, the majority of people would experience a much happier, more peaceful, less stressful existence. Religion does not cause anyone to stress, freak out, or make life worse for others. People do that without any help from what's written in the books that guide their various faiths.

I've heard this more strongly stated as "many things have been done in the name of religion that are against the core principles of that religion".