Isn't metaphysics 'just' things that science can't yet explain? The big inexplicables to me are where did everything come from, how life began on earth, and how homo sapiens became self - aware and imaginative. Scientists have for now posited the 'big bang' theory, theists will say it was god, neither of which explains very much. The first cells formed from amino acids and natural stuff that was lying around; theists will say this is impossible, (the odds against it, blah blah blah...) scientists will say it isn't, we just haven't worked out how it happened yet. Enter 'belief', religion; if science can't explain it god must have done it, just choose your god. (Or more likely have it chosen for you) Once you have first cells, the rest is evolution, which is pure, evidential and explicable science.
The 'self awareness' thing is the reason that we are asking the questions in the first place. Uniquely, we are aware of our own existence, and therefore that we are going to die, and what happens then? Theists will say we go to heaven (again, choose your version of heaven) or hell, atheists will say we don't; death is the end of us in our current physical form, we become something else. Where there is belief there is non - belief, and agnosticism.
We have (somehow) the capacity to imagine, which is where I think belief comes from, and to feel 'spiritual' in the face of beauty or experience, whether we believe in a god or not.
I once read an analogy where science and religion are climbing different sides of the same mountain in their attempts to explain life, the universe and everything, and if they ever meet at the top, neither will have all the answers. Anyway that's it for now, got to take the dogs out....