You know the truth
If you agree there is a God and also realize nothing is for certain in this life you know the truth. This is the essence of what experience and observation can teach. There are an infinite amount of variations and seeming truths, but underlying it all are these two statements. They are the essence of your search. You have found there is a maker and our lives here are somehow impermanent and incomplete.
While this can't be proven you still know deep down this statement is true.