We always act on some mixture of facts and beliefs. It's just a question of how rich the mixture is with facts.
Life being the way it is, though, there is probably no issue that doesn't involve some element of belief because just thinking that we have all of the facts in a given case is itself a belief that is a part of the fact-belief mixture.
But as convoluted as the issue can become, there are commonsense rules to apply -- a prime one being that the more fundamental the issue, the more care we should take to make the mixture as rich in facts as possible.
It is true, though, that this commonsense rule is so often violated in the most basic human affairs -- that is, in matters of sorting out how the universe works and what life is all about -- that a really good case could probably be made that the idea of such a rule existing in real-life human affairs is just a fiction.
Nevertheless, I will do my best to observe the rule here and apply it to laying out a fact-grounded structure to use in explaining what's going on here and why we find ourselves right in the middle of it.
So let's phrase the question like this:
(1) Is there any set of facts in our modern knowledge base that (2) strongly supports a picture of the universe and of the human adventure -- a picture in which (3) our species has a serious, meaningful role to play in the scheme of things and which (4) predicts a future for our species that at the very least would make life irresistibly interesting?
A full, unflawed answer to this question, by my standards, would define "a proper body of positive beliefs" about the meaning of life for folks with any concern for what is right and proper for intelligent life forms. Nothing less will really do.
So, with this highly structured question in mind, let's insist on getting the answer in this form:
This set of facts:
[List of facts]
Strongly supports this picture of the universe and of the human adventure:
[Word picture of the universe and the human adventure]
This picture assigns this seriously meaningful role in the scheme of things to our species:
[Description of the role]
And predicts this highly interesting future for the human adventure:
[List of future events to expect]
As must be obvious, I have an answer to this question to propose, and I have recently laid it out in detail elsewhere. (In fact, I laid it out online some decades ago, but no one seemed to notice.)
The thing I have never been sure about, though. is whether there is another answer -- and God forbid (if I may put it that way), maybe even a better one.
So I would dearly love to know if there are any other technical atheists out there who can put their positive belief system about the meaning of life into the format given above.
I wish I could honestly say, "I'll tell you mine if you'll tell me yours."
But I will, of course, tell you mine anyway, somewhere down the line. Just don't hold your breath. I'm 78 years old, and it always surprises me when I actually wake up in the morning.