You oversimplify much.
Not believing that Jesus existed, and not believing he is the actual offspring of an omnipotent being are two entirely different things. Most atheists acknowledge the likelihood of Jesus existing, just not his divinity. They do this because there is absolutely no proof whatsoever in anything divine (as is in fact required by the very definitions of divinity).
Many mental patients have developed deep and meaningful relationships with entities we label fictitious. We can't actually prove they don't exist, it's just that we can't prove they do. This is generally the way of things. Relationships with a spiritual being fall under the same heading and so are treated much the same way by some. That's not to call religious people crazy, I'm just pointing out the logical path of conclusions.
I have experienced that most atheists do believe we cease at death, but some are not so certain. There are some quasi-spiritual groups that deny monotheism but believe (or at least hope) that some form of consciousness continues after death, though they are often hard pressed to rationalize this duality. You could, I suppose, believe in reincarnation of some type and still be an atheist, as long as you deny the existence of a god. I think that's stretching the defnition of atheism however.
Lastly, being an atheist doesn't mean you don't search for answers, any more than being a theist means you look for answers. Many (in my opinion the vast majority) of people claim religious affiliation without ever seriously questing for truth. It's more about being included for them than it is about answers to any great questions. I never sought answers and truth as hard as I did for the 30ish years I spent as an atheist. During that time I read most religious texts, attended services of every faith I could find, debated frequently, read incessantly, and thought endlessly. None of that in any way suggested a 'truth' to be found in any religion.
In my opinion the answer is that there is NO universal truth. Everything is subjective, including answers of divinity and the nature of life and the universe. You can't find the 'truth' of religion by trying to see that religion thru the eyes (or words) of others. You have to experience something that clicks inside you as being 'true'. In other words, you don't find religion, religion finds you. ***note that I actually don't mean that, because I don't believe in religion (meaning the institution thereof). A more accurate description for it would be belief, or spirituality***