Alyssa Bereznak has a good piece in Salon...

...this morning about her Objectivist father, "How Ayn Rand Ruined My Childhood." As a one-time Ayn Rand sympathizer -- and close friend to a hard-core Objectivist -- I nodded in recognition at much of it. 

Here's the part I found most insightful (my emphasis):

I don't know exactly why [my father] sparked to Rand. He claimed the philosophy appealed to him because it's based solely on logic. It also conveniently quenched his lawyer's thirst to always be right. It's not uncommon for people to seek out belief systems, whether political or spiritual, that make them feel good about how they already live their lives. Ultimately, I suspect Dad was drawn to objectivism because, unlike so many altruistic faiths, it made him feel good about being selfish.

In my experience, most (if not all) Objectivists were merely trading one religion (Christianity or Judaism, in most cases) for another, Objectivism. And they were also trading one god (the Judeo-Christian one of the Bible) for another, Ayn Rand.