Notice that that changes the original principle in question. The original principle in question is that if there is a difference in *conception* of God, then there is a difference in *reference*. Now, to avoid Marcionism, you have added the "ignoring" factor. So the revised principle would be something like this: "If there is a difference in *conception* of God, and if the person holding a false conception of God has been presented with the true conception of God and yet has ignored it, then there is a difference in *reference*.
So imagine an old Jewish man who has never heard the Christian gospel, but has worshipped God his whole life according to the OT. He then hears the Christians gospel and rejects it. According to your revised principle, his rejection of the gospel would entail that as soon as he goes back to the synagogue and begins to worship what he thinks is the same Being he has been worshipping his entire life, he has instead suddenly begun to worship an idol (i.e. some being other than God).
Is that really plausible?
-A8
So imagine an old Jewish man who has never heard the Christian gospel, but has worshipped God his whole life according to the OT. He then hears the Christians gospel and rejects it. According to your revised principle, his rejection of the gospel would entail that as soon as he goes back to the synagogue and begins to worship what he thinks is the same Being he has been worshipping his entire life, he has instead suddenly begun to worship an idol (i.e. some being other than God). Is that really plausible?
While I'm certainly on your side of the debate on this one, your example of the old Jewish man who was presented with the truth of Christ and yet still denied it is kind of troubling. What do we make of the following Scripture?
Peter says...
But those things, which God before had shewed by the mouth of all his prophets, that Christ should suffer, he hath so fulfilled." -- Acts 3:17-18 "And now, brethren, I wot that through ignorance ye did it, as did also your rulers.
Then John further explains...
"Whosoever denieth the Son, the same hath not the Father: he that acknowledgeth the Son hath the father also." -- 1 John 2:23
And...
"Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son." -- 2 John 1:9
From these verses it would appear that those without the Son, having once been shown the truth, are "without excuse."
For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened." -- Romans 1:19-21"Because that which may be known of God is manifest in them; for God hath shewed it unto them.
Of course this raises the possibility that it might be better for the old Jewish man never to have heard the Gospel of Christ and then he'd still be "right" with his Old Testament God.
Which makes no sense, according to Christ's directive to make disciples of all the world.
Bottom line is that it is God who gives understanding and God who gives unmerited mercy through Christ's atonement of the fallen sinner. The best recourse is to do as we're told.