Samuel Langhorne Clemens (November 30, 1835 - April 21, 1910)
According to Wikipedia, Clemens, "better known by the pen name Mark Twain, was an American humanist, humorist, satirist, lecturer and writer. Twain is most noted for his novels Adventures of Huckleberry Finn, which has since been called the Great American Novel, and The Adventures of Tom Sawyer. He is also known for his quotations. During his lifetime, Twain became a friend to presidents, artists, leading industrialists and European royalty.
"Twain enjoyed immense public popularity, and his keen wit and incisive satire earned him praise from both critics and peers. American author William Faulkner called Twain 'the father of American literature'....
"After his death, Twain's family suppressed some of his work which was especially irreverent toward conventional religion, notably Letters from the Earth, which was not published until 1962. The anti-religious The Mysterious Stranger was published in 1916, although there is some scholarly debate as to whether Twain actually wrote the most familiar version of this story. Twain was critical of organized religion and certain elements of Christianity through most of his later life."
A few Twain quotes:
Faith is believing what you know ain't so.
The gods offer no rewards for intellect. There was never one yet that showed any interest in it.
I cannot see how a man of any large degree of humorous perception can ever be religious -- unless he purposely shut the eyes of his mind & keep them shut by force.
God's inhumanity to man makes countless thousands mourn.
Surely the ass who invented the first religion ought to be the first ass damned.
If Christ were here there is one thing he would not be -- a Christian.
Most people are bothered by those passages of Scripture they do not understand, but the passages that bother me are those I do understand.
When one reads Bibles, one is less surprised at what the Deity knows than at what He doesn't know.
[The Bible] is full of interest. It has noble poetry in it; and some clever fables; and some blood-drenched history; and some good morals; and a wealth of obscenity; and upwards of a thousand lies.