If God sends a man who had a saving faith in Christ to Hell for a sin he later committed, He contradicts Himself.
"If God sends a man who had a saving faith in Christ to Hell for a sin he later committed..."
...then that man committed an egregious sin which, evidently, he did not feel he needed to ask for God's forgiveness.
Perhaps murder is not a sin we see too often from saved people. Perhaps. But we do see adulterers who never think that they have committed an egregious sin, nor do they think they have to ask forgiveness from God. I pray they do not die that way.
I don't judge them; after all, I could be wrong. But I sure stay away from them.