I cannot know for certain but I think God is very improbable, and I live my life on the assumption that he is not there. - Richard Dawkins

I'm all for offending people's religion. I think it should be offended at every opportunity

If we want to postulate a deity capable of engineering all the organized complexity in the world, either instantaneously or by guiding evolution, that deity must have been vastly complex in the first place. The creationist, whether a naive Bible-thumper or an educated bishop, simply postulates an already existing being of prodigious intelligence and complexity. If we are going to allow ourselves the luxury of postulating organized complexity without offering an explanation, we might as well make a job of it and simply postulate the existence of life as we know it!

When people say they are atheists they don’t mean they can’t prove that there are no gods. Strictly speaking, it’s impossible to prove that something does not exist. We don’t positively know there are no gods, just as we can’t prove that there are no fairies or pixies or elves or hobgoblins or leprechauns or pink unicorns; just as we can’t prove that Santa Claus or the Easter Bunny or the Tooth Fairy don’t exist. There’s a billion things you can imagine and nobody can disprove.