Of course atheism has something to do with materialism. This is where we encounter the usual problem of what you mean by ''atheism'', because all definitions do not equally interact with materialism.
Ah. Notice that you used the word 'rational'? The problem with that is, to me, materialism is not rational; it is obviously incorrect. Yet, to you, it is the only option, due to what you consider lack of evidence otherwise. Notice the pattern here, whether it's theism, etc., ? Yes, it's entirely subjective to what you have figured 'rational'. I do not believe that you have honestly examined this topic,.