I cannot make a list of “what we believe.” There are no articles of faith, only things that are probably true based on what we all have observed and figured out.
I base my beliefs on what I can observe and what makes sense to me, rather than religious faith. I don’t have faith in scientists or experts in any field. Instead, I trust what they say based on how reliable they have been in the past and how reasonable their methods are.
What is, is.
I am pretty sure that I exist, and that what I experience is real. One might call that a faith-based belief, since I cannot provide evidence for my existence. Descartes said, “I think, therefore I am.” I would say that I think I exist, so let’s go with that. I can’t prove that the way I perceive things is the way they really are, that I’m not a brain in a vat or a computer simulation. Nonetheless, I think that what I see is real, and that has practical value; it allows me to make decisions that keep me alive and healthy.
There is one natural world.
By definition, the cosmos is all that exists, and all things and all beings in it are at least potentially observable and measurable. As far as anyone can tell, there is no “spiritual” existence that interacts in any way with what we understand as reality.
We are not so special.
Since the universe is natural, it follows that human beings are, too. We are the sum of our physical processes, and we do not have little angels (souls) driving us around.
The cosmos may be eternal, but everything else seems to have a beginning and an end. Enjoy life while you are alive.
We have limitations.
We are capable of great things, but we don’t know everything, and we will never know everything. It is helpful to remember that.