The Apostle Paul has spoken at length of the substitutionary atonement of Christ made on our behalf and the many benefits associated with a relationship with Him. Then he asks a question.
Romans 8:31 What shall we then say to these things? If God be for us, who can be against us?
He is challenging us to consider the benefits and security of a relationship with Christ.
We know God is for us. He proved it. It doesn’t matter who or what is against us, He will never leave us or forsake us. His grace is sufficient for every situation.
