just entered this debate, i'd actually have to admit i agree with arguments from both sides. however, this one i thought i'd answer.
scientists have used telescopes to seek back to the "big bang" that some believe exists. they have shown "images" of this at 1s after, .5s after, .00005s after, etc. but they have never shown time 0. nor any time before the "bang". they suppose what may have existed at and before, but these suppositions are as yet unconfirmed. further, as JColtrane points out, science cannot explain the reason for existance. why is matter here? where did it come from? trying to comprehend the case of "it was always here" presents the problem of "what came before that, and before that, and before..." until we reach a situation where we'd have to take the limit of the situation as time goes to negative infinity. we can predict this, perhaps prove it mathematically, but never observe it to verify its reality. so science can't explain the origin of matter. you may not care about such things, but this shows the limitation of science, if science is the method for understanding reality as we best can. even science requires faith to achieve these impossibilities (such as the example above, a scientist would conduct experiments until he observed the "limit" trend as time went to negative infinity and then suppose what that limit is, based on data, despite not knowing precisely.)
so i'd say theism requires faith due to its nature, and atheism as well. some deny it, and others abuse it, but it is a device of thought apart from religion, though central to it.