Does Predestination Make God Unjust? — Louis Berkhof
“It is sometimes said that the doctrine of predestination exposes God to the charge of injustice. But this is hardly correct. We could speak of injustice only if man had a claim on God, and God owed man eternal salvation. But the situation is entirely different if all men have forfeited the blessings of God, as they have. No one has the right to call God to account for electing some and rejecting others. He would have been perfectly just, if He had not saved any, Matt. 20:14-15; Rom. 9:14-15.”
- Louis Berkhof (1873-1957)
taken from: Summary of Christian Doctrine
I would completely agree with you, except that the thing about predestination is that it occurred before creation, meaning that it goes beyond God choosing some and rejecting others based upon their actions because God chose them to act as they do, creating “vessels fitted for destruction” (Rom. 9:22). It is not therefore man that calls God to account for this injustice, but the concept of justice itself that God supposedly created. It is an ugly contradiction, a legislator above his own laws viewed as merciful regardless of the punishment he imposes upon those who are held responsible for crimes he himself committed.