When did humanism come to mean atheism? Erasmus wasn't an atheist.
I've been to a humanist funeral (eulogy and a reading from Tolkien), and the celebrant gave an embarrassed laugh when (out of habit) I shook his hand on leaving the crematorium.
Modern atheism doesn't seem quite rational to me. I can't find it easily, but there was an ancient Greek philosopher who, denying the soul, told his followers to throw his body into the road when he died, and when they raised the possibility that wild animals might come to eat him while still alive, told them to put a stick in his hand. That's being consistent with your beliefs.
"The Humanist view of life is progressive and optimistic, in awe of human potential, living without fear of judgement and death, finding enough purpose and meaning in life, love and leaving a good legacy," says the President of the British Humanist Association. Why all this preachiness?
Doubtless I'll be enlightened by some of these paradoxical zealots in the comments.