Atheism has seen a resurgence over the last several years. The so-called "new atheism" represented by the best-selling works of Richard Dawkins and the late Christopher Hitchens is more militant and more evangelical than the "old atheism". No doubt you've encountered at school or in your office an atheist who makes no bones about his lack of belief and challenges you at every turn.
If you want a good way to get them to think through their position, show them this video from "Fr. Pontifex", aka Fr. Claude Burns. Fr. Pontifex is known for his cutting edge use of videos to spread Gospel. You can see other examples of his work at http://www.frpontifex.com/