Sure, that will always be the case. If someone succeeds in convincing you that she has in fact demonstrated the existence of a God, the God, her God, then that need be as far as it goes. You now believe this God exists and will behave accordingly on this side of the grave in order to behave accordingly on the other side of the grave.
And then you may or may not be able to convince me and others of it.
But out in the world that we live in today, there are dozens and dozens and dozens of different Gods that folks claim in their own way to have demonstrated the existence of.
Then all the resulting conflicts regarding what to do on this side of the grave in order in order to attain one or another rendition of immortality and salvation on the other side of it.
Then it’s all about “one of us” vs. “one of them”. Unless you are ecumenical in your outlook. Then you are in God’s cafeteria picking out the behaviors that are the least problematic for you.
But: where is the demonstration that clearly pins down a God, the God, my God?
Well, for those who have faith in one or another denomination, it is accepted that the existence of their God has been demonstrated just enough for them to embody the comfort and consolation that faith/belief in God brings about.
But, of far more importance [to me], whether this apple exists on this table in this context matters not in grounding your moral values in a font applicable to all of us. And matters not regarding the fate of “I” upon dying.
There is the crux of it. It’s not the actual existence or demonstration of existence which is different. It’s what people do with it later which troubles you.
Once you realize that, then you can go on to identifying which behaviors bother you and what can be done about them, if anything.
Okay, but what can you do when an apple has been demonstrated to exist? What behaviors of yours will be impacted? Again, if the existence of the apple and the existence of God are somehow equated in your mind, and it is important to you here that they are, then that serves its purpose: to anchor your own particular “I” to a font able to guide your behaviors on this side of the grave and sustain “I” on the other side.
On the other hand, I still have no clear idea of how that actually “works” for you when confronting conflicting goods.