I wish I had read this back when I was 18. It's an amazing take down of religious beliefs, the Bible, and religion in general. But it does this in (can I say this?) a "Reason"-able manner.
Take this quote, from near the beginning:
When also I am told that a woman, called the Virgin Mary, said, or gave out, that she was with child without any cohabitation with a man, and that her betrothed husband, Joseph, said that an angel told him so, I have a right to believe them or not: such a circumstance required a much stronger evidence than their bare word for it: but we have not even this; for neither Joseph nor Mary wrote any such matter themselves. It is only reported by others that they said so. It is hearsay upon hearsay, and I do not chose to rest my belief upon such evidence. It is, however, not difficult to account for the credit that was given to the story of Jesus Christ being the Son of God. He was born when the heathen mythology had still some fashion and repute in the world, and that mythology had prepared the people for the belief of such a story. Almost all the extraordinary men that lived under the heathen mythology were reputed to be the sons of some of their gods. It was not a new thing at that time to believe a man to have been celestially begotten; the intercourse of gods with women was then a matter of familiar opinion. Their Jupiter, according to their accounts, had cohabited with hundreds; the story therefore had nothing in it either new, wonderful, or obscene; it was conformable to the opinions that then prevailed among the people called Gentiles, or mythologists, and it was those people only that believed it. The Jews, who had kept strictly to the belief of one God, and no more, and who had always rejected the heathen mythology, never credited the story. It is curious to observe how the theory of what is called the Christian Church, sprung out of the tail of the heathen mythology. A direct incorporation took place in the first instance, by making the reputed founder to be celestially begotten. The trinity of gods that then followed was no other than a reduction of the former plurality, which was about twenty or thirty thousand. The statue of Mary succeeded the statue of Diana of Ephesus. The deification of heroes changed into the canonization of saints. The Mythologists had gods for everything; the Christian Mythologists had saints for everything. The church became as crowded with the one, as the pantheon had been with the other; and Rome was the place of both. The Christian theory is little else than the idolatry of the ancient mythologists, accommodated to the purposes of power and revenue; and it yet remains to reason and philosophy to abolish the amphibious fraud.
Pretty ballsy stuff to be written 213 years ago.
http://s3.amazonaws.com/manybooks_pdflrg_new/painethoetext03twtp410pdfLRG.pdf