It is evident to me that the staying power of Paine's Age of Reason is strong-- I need only look through the mixed opinions here at Amazon to see how dramatically it impacts those who read it. For me, it was a great wake-up call. I read Age of Reason at the beginning of this year and didn't know much about what to expect. From the first few pages I knew that I had found a book that reflects how I feel about religion. Paine offers a sensible alternative to atheism and the vast supply of revealed religions that abound in the world. To be logical, Paine points out, you need not give up a belief in a Higher Power. But you also don't have to sell your soul to charlatans and holy books written hundreds of years ago by men, not gods.
The first half of Age of Reason outlines Paine's own beliefs as well as those he rejects. He gives reasons for every point he agrees or disagrees with and it is clear to the reader how Paine feels. Paine wants to spell out what his thoughts are so that he won't be misjudged by his peers. (Jefferson went through a similar ordeal-- because of his connections with France, he was labeled "a French infidel and atheist" neither of which was a true statement. See _The Religious Life of Thomas Jefferson_ for more info.)
In the second half, Paine sets out to show the Biblical discrepancies to those who wanted to prove his ideas false by using the Bible as their "evidence". In a relatively small number of pages, Paine debunks and demystifies (in my opinion) a fair amount of 'Christian' theology and scripture. If one man can do it so well in only a few pages, what does that say for revealed religion? That question is for each of us to answer individually and Age of Reason is required reading for anyone who is serious in doing just that.