Your comments on this issue are a perfect example of the problems
you have with communicating with people in life. Your language is
far too abstract for most folks. You talk like an academic.
Academics rarely persuade people about anything, least of all on
issues relating to God.
You should try reading Dennis Prager (Think A Second Time). He
is far more persuasive on issues (religious or not) because he
speaks clearly and "admits" when he doesn't "know" something.
He is actually as logical as you, but he doesn't muddy things
with obscure verbiage.
Make your thoughts clearer. Your use of the word "KNOW" (as in
you KNOW God exists) is not what logical people mean when they
say they know something. Your knowledge of God's existence is
really your FAITH that he exists. And that is as it should be.
That is what faith means: you "cannot" KNOW He exists, but you
can use logic to "fortify" your faith. But we can never know,
in the sense that non-believers use the word. That is what
Your answer to "Why no Proof He exists?" is way too abstract.
Be more direct. Say "We don't know" or "Of course that is a
mystery". Use logic to express "why" your faith makes sense,
but don't say you KNOW He exists. Nothing will turn skeptics
"What caused the Universe?" is a perfectly valid piece of reasoning
to "fortify" your faith. But we all know that it is not proof.
It is strong evidence, though.