Religion as brainwashing

I saw an atheist post recently that all religion was brainwashing. I argued the point, though the person was willing to concede nothing. I have since found that studies by Pew have found that depending on how you define it, over 40% of Americans change religion. Now some of that may be between mainline protestant, evangelical, and Catholicism. Still a steadily increasing number of people are unaffiliated and do not adhere to any specific religion, though they don't consider themselves atheists or agnostic either. That does not even account for changes between various denominations of Christianity within the three major grouping listed above. If religion is brainwashing, then it seems to be failing a lot of the time. For myself, I was raised as a mainline protestant Christian, but left that to follow Buddhism, Zen, and Taoism, before converting to Judaism. As a teen, I was rejecting Christian dogma, which led to my deciding that I could not in good faith consider myself Christian. None of any of this will convince the militant atheist of anything other than what they believe.