Let me ask you... Do you think Thor belief is irrational? How about Wiccans? Are they irrational? Mormons? Scientologists? Do you believe that a Thetan resides within all of our bodies? Is that rational? How is the idea of Thetans any more or less rational than the idea of a 'soul'? It's the same thing. Both irrational. All an atheist does is say that Christians are irrational in exactly the same way as all the others are.
Another thing to consider is how you came about your belief system. If you, like most believers, simply carry on with whatever faith by which your parents raised you then you should honestly question whether you would have come to the same conclusions from an independent position. If you had been born and raised in the middle east you would almost certainly be a Muslim. You must objectively (very hard to do!) ponder the root and nature of your faith to truly determine its validity. If your former roommate had been just as devout and confident as a Hindu would he still have been as compelling to you? Would you have converted?