Well DHK; we have been here before and probably will not agree this time, but what you say that the "sin unto death" is a early death, does not make sense.
1. Unless God took his life before he committed the "sin unto death", this man would have two problems.
a. He would die an early death as you say because he committed this "sin unto death".
b. He still would have one problem left, and that is "repentance" again, of which there is no repentance after death.
2. You answer to this would still leave a Christian (as you say) still unrepentant, therefore subject to the second death.
Now if it were as Jesus said impossible for this to take place, then a Christian could sin, but not a "sin unto death".
As Jesus said, there is a sin, and there is a "sin unto death" that I would not say to pray for.
I do and would rather believe that the Grace of God which saves a man, does not leave him, but rather stays with that saved man to keep him until the Lord comes again. I don't think that is a "sinless man" and neither do I think it is Catholic belief.
Think about it DHK; you solution would still leave that man a "unrepentant man", which would be subject to the second death. You answer of an "early death" would not help that man/woman at all, for they would still be a "unrepentant sinner".
BBob,
Why not quote this verse of John also DHK:
1Jo 3:9Whosoever is born of God doth not commit sin; for his seed remaineth in him: and he cannot sin, because he is born of God.
If someone shoots you, then you will die an early death, for fear not man who can destroy the body.