Robert Louis Stevenson was a Scottish novelist, poet, and travel writer, best known for his classics Treasure Island, Kidnapped, and the Strange Case of Dr. Jekyll and Mr. Hyde. He is the 25th most translated author in the world. 
The following is a passage from a letter written on February 2, 1873 by Stevenson, shortly after his father discovered a pro-atheist document of his, from a club founded by his Cambride-educated cousin, Bob:
"MY DEAR BAXTER, - The thunderbolt has fallen with a vengeance now. On Friday night after leaving you, in the course of conversation, my father put me one or two questions as to beliefs, which I candidly answered. I really hate all lying so much now - a new found honesty that has somehow come out of my late illness - that I could not so much as hesitate at the time; but if I had foreseen the real hell of everything since, I think I should have lied, as I have done so often before. I so far thought of my father, but I had forgotten my mother. And now! they are both ill, both silent, both as down in the mouth as if - I can find no simile. You may fancy how happy it is for me. If it were not too late, I think I could almost find it in my heart to retract, but it is too late; and again, am I to live my whole life as one falsehood? Of course, it is rougher than hell upon my father, but can I help it? They don't see either that my game is not the light-hearted scoffer; that I am not (as they call me) a careless infidel. I believe as much as they do, only generally in the inverse ratio: I am, I think, as honest as they can be in what I hold. I have not come hastily to my views. I reserve (as I told them) many points until I acquire fuller information, and do not think I am thus justly to be called 'horrible atheist.'"
The letter is signed:
" Ever your affectionate and horrible atheist,
R. L. STEVENSON. 
"He was both engineer and aesthete, dutiful son and reckless lover, Scotsman and South Sea Islander, Covenanter and atheist." - From the front flap of Myself and the Other Fellow: A Life of Robert Louis Stevenson by Claire Harman.