Why religion is the problem we have in the world?

the religions we know/follow today were made in past at some time to only support/hold the humans together by means of devotion and faith. But today the impact has gone wrong: It seems religion is the biggest problem that Humanity is facing and it seems like religion is just a concept to "categorize" humans in different category.

Religion is a problem in todays world because there are so many different beliefs by everyone. It causes disagreements between people because they don't see how other people could possibly believe in a different god, or even a god at all. You have the atheists who don't believe in any god, christians who believe christ died on the cross, muslims who believe allah is the one and only god, catholics who believe Mary is the savior ... So many different belief systems that it causes conflict due to the fact everyones faith in what they believe in is so strong. There will never be a peaceful agree to disagree when it comes to religion, the same thing politics is such an issue in todays world.