We can reject God based on our failed understanding of God
God says that He has made clear to them what can be known about Him and that any misunderstandings of His key attributes or what He says is sufficient for more, comes from THEIR willful, intentional rejection ("THEIR unrighteousness) of the things that make up that truth. Clearly, Scripture says that this ALONE is enough for them to be condemned.
And WHAT misunderstanding? "For
what can be known about God is plain to them,
because God has shown it to them. For his invisible attributes, namely,
his eternal power and divine nature, have been clearly perceived, ever since the creation of the world,7 in the things that have been made." IMMEDIATELY followed by:
"So they are without excuse."
"those that reject out of ignorance and/or confusion"
Scripture says that ANY confusion about what they initially need to know (which would lead to them knowing more) is because MEN, "who by
their unrighteousness suppress the truth." It's not because they weren't given enough information or that God left them in confusion. The above Scriptural supports would seem to contradict your contention. And so UNLESS there are further things God does that we cannot see, then all we are left with is hopeful speculation that there is another opportunity for the heathen to understand what it appears to US mortals that they originally did not.
One thing is certain to me, that God is more than fair with ALL men and He has cut no one off for mere misunderstandings or lack of knowledge. But we just don't see all that God does or that He has been doing. Of course, that cuts both ways, as MAYBE, but without anything approaching certainty, there is more to this than can be determined by us (which is why the NDEs are interesting). But I'd never definitively say more than what Scripture has revealed to us on this subject.
Paul, I can see where your heart is on this - that, at least on the surface, we perceive that those without the Gospel have not had the very same chance. And, of course, Jesus said that those without the Gospel will receive a lesser punishment. And we know God is fair and yet being condemned for not embracing something (the Gospel)that they have not known about seems grotesquely unfair. However, that is not what Scriptures on this teach - that's not the reason that God considers them guilty.
Plus, you can't split up the Father, Son and Holy Ghost. To reject any one "person" within the Trinity is to also reject God in His entirety. To know of all portions of God (Father, Son, Spirit) and to reject any one is to also reject God. But we can only reject the parts/depths of Himself which God has already revealed to us. Romans says the Heathen have already done that, and so further illumination was not forthcoming. It would appear that God deems more information as unnecessary, as that would be rejected as well. Remember, those that lived amongst Jesus, saw unbelievable miracles, knew of Lazarus' raising, etc, etc, yet many STILL would not believe. Moses led Israel out of Egypt per astonishing miracles, drowned the pursuing Egyptian army after first parting the Red Sea - and YET, Moses is barely out of camp before they're building a Golden Calf. So we can see that we shouldn't assume, just as with ancient Israel and as also with those heathens without the Gospel, rejection need not be a knowledge problem, it's a HEART problem! And God has already told us about the human heart's deceptive ways.