You keep giving what I see as a false choice.. either God must forgive everyone... or that He has placed requirements on being saved that man must obey
Cab there be a 3rd choice ...one that was quoted by Paul
"I will have Mercy on whom I will have mercy"
I agree He can have mercy on who he wants to have mercy. But that doesn't take away from the fact that we are called to obedience, and that the Bible tells us that when we don't obey God, we are rejecting Him.