Oh, I was. Catholic. Why do you ask, do you suppose religious people aren't prone to thinking that the "religious viewpoint" generally means their own?

Well, anyway, I was only religious until about the age of 9 or 10, so that doesn't mean much. What should mean more is that later in life even as an atheist I had a lot of interest in religion and spirituality, and I became familiar with a lot of varied ideas; I'd read the Bible and Bhagavad Gita for pleasure, and debated with my religious friends avidly. It was all rather interesting, since at that time I wasn't a strong atheist by any means and I suspected there might be something to it.

But eventually my views shifted towards strong atheism, and I felt I'd more or less exhausted the topic. Since then I notice my brain got lazier when it came to processing religious ideas. If by some chance I find myself in debate with a religious friend (not long ago I had a big one with a Jewish friend of mine who's very unimpressed with Eliezer ;) and more importantly, has wrong ideas about evolution), it takes effort to actually listen to what he's saying and make sure I understand where he's coming from - rather than accessing my theist-viewpoint cache and arguing with that instead of my friend.

I think this is a general rule: we tend to spend fewer cognitive resources on processing ideas we regard as wrong. (Now that I put it that way, it seems trivially obvious). Just like so many religious people have preconceptions regarding what atheists think or believe, that atheists themselves repeatedly have to refute. Same thing. Brains are lazy.