If God will not bring everyone to a saving faith in Jesus Christ, is it because He is unable to do so or because He is unwilling?
Those are the only two choices if you believe God will not save everyone. Period. And you know it.
But folks will attempt to skirt the question and weasel out of the disucssion. People will try to use free will or use such obscure non-arguments as "God's justice is not like our justice". Neither of these arguments, or any other for that matter, change the obvious fact: God is either unable or unwilling to save everyone, if that is not the outcome.
Let's take a moment and break down the objections.
1 - If free will prevents God from saving someone, God is impotent and their will is stronger than His will. The Bible tells a different story and says that no one can resist God's will. (Romans 9 for instance)
2 - If God is unwilling to save someone, then we have a contradiction in the scriptures and we must discard the Bible as being irrational and self-contradictory. The following scriptures, and many more, say God is indeed willing to ultimately save everyone through Jesus.
2 Peter 3:9 ...not willing that any should perish, but that all should come to repentance.
Luke 19:10 Jesus came to "seek and save the lost"
John 3:17 For God did not send his Son into the world to condemn the world, but to save the world through him.
Now either God CAN and WILL do what the Bible says here and other places - or He CAN'T or WON'T.
Those are your choices - choose to believe the Scripture and you are choosing to believe that God Can and Will bring all to repentence and faith in Christ, just like the scripture says. Pretty simple isn't it?