A Hyman of Security
Divine sovereignty is the ultimate source of comfort for the Christian believer, because it means that God is in control of his destiny. What could be more comforting to the Christian than to know that the outcome of his life is not in the hands of fortuitous circumstances, but is in the hands of a benevolent God?
Paul is saying that our ultimate destiny is in the hands of a holy, omnipotent, sovereign, righteous, loving, personal God and that this is a cause for rejoicing.
The good news is found in the words, If God is for us. Paul is describing the ultimate sense of experiencing someone who is for us, and in this case it is God. This is the message of predestination: God does not leave me to impersonal, fortuitous circumstances. God determines, in a very real way, my destiny which is glorification. Whatever else happens to me in this world, I know that God is for me. That knowledge is humbling, as well as comforting.
Paul has just banished doubt in the passage before this. He has shown how God has set his love upon us, predetermining that we are to be conformed to the likeness of his own beloved Son. Then, having made the predetermination, he has called, justified, and glorified us. In this verse “if” means “since”—“since God is for us”—and that makes the difference.