1. God shows no partiality (Romans 2:12)
2. The Calvinist doctrine of election states that God chooses some for salvation and some for damnation, unconditionally.
3. Thus this demonstrates that God is showing partiality, which is a contradiction.
Now, this is actually a pretty good objection, for the conclusions actually follow from the premises...
if indeed the premises actually are true in the sense that the objector means. And I think a Scriptural examination would demonstrate clearly that the "no partiality" in Romans 2:12 (and related passages) simply means that every one is going to be judged against the same standard, "be perfect as God is perfect."
To defend the objection another way, we can turn it upon itself and say "ok say it works against the doctrines of Grace, but what do we make of all these Bible passages that say Israel was chosen apart anything else -
6 “For you are a people holy to the Lord your God. The Lord your God has chosen you to be a people for his treasured possession, out of all the peoples who are on the face of the earth. 7 It was not because you were more in number than any other people that the Lord set his love on you and chose you, for you were the fewest of all peoples, 8 but it is because the Lord loves you and is keeping the oath that he swore to your fathers, that the Lord has brought you out with a mighty hand and redeemed you from the house of slavery, from the hand of Pharaoh king of Egypt.But this passage is entirely consistent with Calvinism, since Calvinists are just simply saying, "just as God chose a specific people contained in ethnic Israel in the past, now He chooses a people with an unrestricted ethnicity."
And finally, Paul deals with this exact objection in Romans 9 -
10And not only so, but also when Rebecca had conceived children by one man, our forefather Isaac, 11though they were not yet born and had done nothing either good or bad--in order that God's purpose of election might continue, not because of works but because of his call-- 12she was told, "The older will serve the younger." 13As it is written, "Jacob I loved, but Esau I hated."After laying the groundwork for loving Jacob and hating Esau, before they were born, apart from works, Paul raises the objection:
14What shall we say then? Is there injustice on God's part? By no means! 15For he says to Moses, "I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion." 16So then it depends not on human will or exertion,[b] but on God, who has mercy. 17For the Scripture says to Pharaoh, "For this very purpose I have raised you up, that I might show my power in you, and that my name might be proclaimed in all the earth." 18So then he has mercy on whomever he wills, and he hardens whomever he wills.And the way Paul chooses to answer it is quite interesting. He simply brushes it aside and says "no, this is perfectly fair, because God is God!" Or to put it another way, "you can't use your standards of fairness to judge God." This isn't to say that God isn't fair, but that God is fair, and our view of what is fair or not is flawed.
But really, no one can consistently level this objection and still remain a Christian. For if God is truly impartial as some claim He must be, then the reason that I am saved and someone else is not cannot be grounded in God, as He gives everyone the same opportunity, but must therefore be grounded in my own free will. So blessed be God for doing that 99% but thanks for nothing for the 1%. Of course not! Salvation is of the Lord, all the way through. And we all affirm that. There is no grounds for boasting, no work, no merit, nothing that demands anything from God except our sin demanding His wrath. And it's by grace we are saved. And faith, well that's a gift of God as well. And my acceptance of faith? That's a gift too. And my acceptance of the gift of accepting...? Grace all the way down.
Praise be to God, who saves us in spite of our wills.