I met alot of people who don't believe in God, and when i engage in a discussuin with them about religion, they jump into conclusions saying that religion is the source of evil in the world and they start giving me some examples.
The question which is begging to be answered now is, as we can see that religion "in general" is not the source of evil and human beings just used it in the wrong way, so then, what's wrong with religion?
I think evil is one of those words that people can't agree on the definition of but can list out examples. Until someone articulates to me in words what evil is to them qualifying it in a sentence is hard to do. However, if they can qualify evil than I think the subsequent communication on the topic it is attached to is high. Meaning lots of info is shared.
As far as religion's con's, and I think con as a word is more adaptable in the context of the OP, I would fault if for the following:
1) Too exclusive. This is true of only some religions but true of the Abrahamic religions in general. The idea behind membership is belief in a higher power, shared values and beliefs with no or little variation and the concept of special privileges of those of the same faith. In many faiths you are either with the program, believe in the right god or you are an outsider. If they do make friends with an outsider there is that constant pressure from many if not most of them to believe and "be part of the program."
2) morality is painted as black and white as opposed to something shaped by the environment and context it is in and than amended by communications with the God of that faith. For instance in the "not murder clause" few religions actually qualify murder from killing (though holy men "Interpret" it from time to time), nor look at the context making the moral introspection of the idea of taking a life so abstract it is not examinable. However, it can be amended (for instance many Christians are pro death penalty) based on communications that religious leaders have with God. To a non-believer it presents the idea that significant moral questions that are needed in a society are glossed over, trivialized and pawned off to a higher power that doesn't qualify the moral idea to his subjects with anything other than the single word "faith" or the duel words of "God's will"
3) faith is elevated to a higher status that evidence in areas where they are mutually exclusive. Evolution vs theological theories on the birth of man being the largest example.
4) The two largest religions, Christianity and Islam are in a current and apparently a permanent power struggle all over the world killing each other on a whim based on which group they belong to. Not just killing combatants, but women, children and advocating genocide at times which is procured as just by their God according to the groups involved.
A large reason for # 4 is because 1,2,and 3 exist in those groups.
As a footnote, one cannot lump all religions into this category because, say findings a Pagan coven that falls into this paradigm or a UU would be somewhere between challenging and impossible but, somewhere between many and most of Christians and Muslims, who together, make up well over 50 % of the believers, are structured in this way.