Stephen Jay Gould (1941-2002), paleontologist and historian of science who was well-known for his essay-writing. Along with Niles Eldredge, he proposed the theory of Punctuated Equilibrium, which states that changes in fossilizable features occur in bursts, in small offshoot populations that grow to become big, well-represented ones. He has also been a champion of multi-level natural selection as opposed to Richard Dawkins's greater emphasis on genes.
He was a secular Jew, and when asked whether he was an agnostic in this interview in Skeptic magazine], he responded
If you absolutely forced me to bet on the existence of a conventional anthropomorphic deity, of course I'd bet no. But, basically, Huxley was right when he said that agnosticism is the only honorable position because we really cannot know. And that's right. I'd be real surprised if there turned out to be a conventional God.
I remember a story about Clarence Darrow, who was quite atheistic. Somebody asked him: "Suppose you die and your soul goes up there and it turns out the conventional story is true after all?" Darrow's answer was beautiful, and I love the way he pictured it with the 12 apostles in the jury box and with his reputation for giving long speeches (he spoke two straight days to save Leopold and Loeb). He said that for once in his life he wasn't going to make a long speech. He was just going to walk up to them, bow low to the judge's bench, and say, "Gentlemen, I was wrong."