Francois M. Voltaire, the French 18th century author and playwright is often considered the father of Agnosticism.
Thomas H. Huxley, a well known English religious skeptic, invented the term in the 1840's. He combined "a" which implies negative, with "gnostic" which is a Greek word meaning knowledge. He wrote:
"When I reached intellectual maturity, and began to ask myself whether I was a atheist, a theist, or a pantheist; a materialist or an idealist; a Christian or a freethinker, I found that the more I learned and reglected, the less ready was the answer; until at last i came to the conclusion that I had neilther art nor part with any of these denomination, except the last...So I took thought, and invented what I conceived to be the appropriate title of "agnostic". It came into my head as suggestively antithetic to the "gnostic" of Church history, who professed to know so much about the very things of which I was ignorant..."
Robert G. Ingersoll is perhaps the msot famous American Agnostic of the 19th century. He commented:
"There is no subject -- and can be none -- concerning which any human beign is under any obligation to believe without evidence...The man who, without prejudice, reads and understands the Old and New Testaments will cease to be an orthodox Christian. The intelligent man who investigates the religion of any country without fear and without prejudice will not and cannot be a believer....He who cannot harmonize the cruelties of the Bible with the Bible with the goodness of Jehovah, cannot harmonize the cruelties of Nature with the goodness and wisdom of a supposed Deity. He will find it impossible to account for pestilence and famine, for earthquake and storm, for slavery, for the triumph of the strong over the weak, for the countless victories of injustice. He will find it impossible to account for martyrs -- for the burning of the good, the noble, the loving, by the ignorant, the malicious, and the infamous."
Charles Darwin, a 19th century British biologist and writer wrote in two places in his book "Life and Letters":
"The mystery of the beginning of all things is insoluble by us; and I for one must be content to remain an Agnostic."
"I think an Agnostic would be the more correct description of my state of mind. The whole subject [of God] is beyond the scope of man's intellect."