I like to be well-informed about as many topics as possible. I'm not really sure why this is; perhaps it's my journalism background or the fact that I don't like to be made foolish under any circumstance. Whatever the reason, I don't like to be unprepared for anything and enjoy knowing at least a little bit about most topics.
Being raised Roman Catholic, I felt well-versed with most of its doctrine/dogma/myths. So it was only natural when I began having doubts about my religion that I would begin my critical thinking by putting Catholicism and Christianity under the microscope. I knew what Catholics practiced, thought, believed, etc., and my faith had been fractured early in life, so it wasn't too much of a stretch to go from doubter to atheist/non-believer.
My research was so thorough that, as a consequence, I learned some of the major differences of Christian sects, Judaism and even some edicts of Hinduism and Islam. My knowledge of these other religions isn't exactly complete, though I have read my share of the Koran and Bhagavad Gita. But given my current beliefs (that there are no gods and supernatural acts are non-existent), do I really need to bother with learning about these other religions? If I were going to be a professional debater or if I wanted to actively seek religious confrontations, then maybe I would deem it important to learn everything I could about all religions and practices.
But will people question my atheism if I never explored thoroughly the practices of Islam or Hinduism? I don't think it's necessary. Does a person who is allergic to shell fish keep eating different species until he's tried every kind? No, why risk death for the sake of completion? That's not to say I'm the least bit intimidated or scared by other religions. But what's the point of studying Muhammad or Ganesh when I don't believe there's any evidence of their miracles or existence?
Besides, I'm sure if proof actually existed or came to light I would learn of it rather quickly and do my homework then. For now, I'm happy knowing the minimum about other religions and being an atheist.