The Bible forbids partiality because God himself knows no partiality in the wrong sense of the term. Paul writes in Romans 2:11, there is no partiality with God. This [does not mean] that God does not distinguish, because we know that, in his sovereign grace, God distinguishes those whom he will save from those whom he will not save. But he does not do so because of anything in the creature. There is nothing in the life of the one who has been chosen that commended that person to God. There is nothing about the one that God passed by that determine God not to save him. We all are filthy and corrupt, regardless of our wealth, our standing, our prestige, our education. Whatever standards the world goes by—those do not mean a thing to God. That is what Paul means. There is no partiality with God. His election is unconditional, in that it is not conditioned upon anything in us. They are wise conditions, operating in the mind of God, but partiality does not play a role in God's discriminating election.1
Joseph A. Pipa
1 My brothers, show no partiality as you hold the faith in our Lord Jesus Christ, the Lord of glory.