Another individual recommended a blog to me asking whether religion does harm to people. (In fairness, the blog author seemed to be asking "Is this true since I became a Christian?" Not asserting it was true). He gave this quote as a lead-in to the article:
"I have watched a good many atheists who were harmless, inoffensive people. They committed a few adulteries or a little quiet pederasty and they were not to be trusted with unattended typewriters or valuable books, but, by and large, they were inoffensive. Then they would start going to church and listening to the clink of thuribles and inhaling incense and suddenly they would acquire all those wonderful Christian virtues—bigotry, pride, intolerance, chronic anger, sexual dishonesty."
— Kenneth Rexroth, An Autobiographical Novel
The problem of course is the associating of these "Christian virtues" with Christianity, and not in the failing of the individual practicing it.
These are not Christian vices. They are vices found in all men, whether Christian, Jew, Buddhist or even Atheist.
The thing is we notice them only when a person changes a world view. When person X practices the same vices we do, but practices them with the same outlook as we have, we write it off as "That's how people are."
However, when a person changes his worldview, the vices he possesses has not gone anywhere, but are practiced in light of his new perspective those vices are no longer tolerable. We hypocritically denounce them as being "caused" by this change.
Certainly the atheist can possess all of these "wonderful Christian virtues" as well. They can be prideful that they "know better" than the believer. They can be intolerant of the Christian who practices openly what he preaches. They can be continually angry at the Christian who challenges them, and they can be sexually dishonest (the atheist may deny there are any binding sexual mores, but I think he would be quite upset if he found his wife in bed with another man).
It would of course be hypocrisy to look down on Christians for these vices when they are present in all.
I believe the common stereotype of Christians being judgmental comes not from their actual change for the worse, but because they are seeking to devote themselves to God, and that necessarily means a turning away from the old man who lived contrary to the way God willed.
This turning however does not mean we automatically lose our former behaviors. I try to gentle myself because being a Christian means loving others, but that doesn't mean I automatically lost my exasperation with bad logic and unchallenged assumptions. Rather, the target has changed.
[People who think I am arrogant or condescending now as a Christian would have probably liked me much less twenty years ago, when my focus was on politics. It was the Christian faith which taught me that truth is not constrained in a party platform.]
I do believe the teachings of the Catholic faith have tempered me from the man I was before, teaching me not to confuse the error with the person who held them [that is: An idea may be idiotic, but that does not mean the person holding it is an idiot].
So I would say, no, religion does NOT make us worse people. It is our refusing (or our inability) to die to ourselves that makes these vices noticeable in Christians. However they are not "Christian" vices, but human vices.