The existence of God is an assumption. He is an assumption because we cannot factually ever know him, even if we can agree that his existence or nonexistence is indeed a fact. The problem with most disagreements, and especially religious disagreements, is that at some point you work your way back through the reasoning and logic and eventually there’s the impassable wall of assumptions.
A fetus either is a life, or it is not. If you assume that it isn’t, you’re likely to favor a woman’s right to choose. If you assume that it is, you’re likely to want to protect that life. All the debate and discussion can ultimately go no further than this point. There is no compromise.
Either there is a God, or there is not. Either a fetus is a life, or it is not. There’s no middle ground between these absolutes.
But there’s also the issue of faith. Few things in life can truly be known. There are very few bridges that span the entire chasm of skepticism. But many get very close. You can’t “know” you aren’t in the Matrix or a butterfly’s dream, but you can be sure enough to take the final step. You can’t know the speed of light is…whatever it is. But you can study it and be reasonably certain.
Faith is a part of everything, but it’s more a part of some things than others. Unless you have done your own research on an issue, you just accept on faith that something is the way it is. I didn’t fight in the Civil War, so I have to accept on faith that it happened. The bridge goes pretty far across. There’s a lot of evidence. But nothing direct for me.
God is an assumption, and that assumption is going to affect the evidence you see. Some people look at the human eye and say it’s obvious God personally crafted it. Others that evolution shaped and perfected it. There is a factual truth, but we can’t know it, we can just collect evidence and believe. We can discuss, but eventually it’s all going to come back to those assumptions and beliefs. No matter what factual evidence is presented, there isn’t enough to sway people one way or the other. There’s always another possibility open. A person has to decide to change their beliefs on their own, and evidence can affect that decision but it can never necessitate a change. The death of a family member or near death experience yourself is much more powerful than the likelihood of life developing on its own.
Whenever you discuss any issue, you have to be able to admit that whether or not there is a right or wrong, reasonable discussion can only go so far. Once it gets there, you have to be willing to just stop talking, because if you don’t, all you’ll get is uncivil discourse.