A.T. Robertson Commentary Romans 8:31

"What then shall we say to these things? If God [is] for us, who [is] against us?" — Romans 8:31 (ASV)

For these things (προς ταυτα). From 8:12 on Paul has made a triumphant presentation of the reasons for the certainty of final sanctification of the sons of God. He has reached the climax with glorification (εδοξασεν in verse 30). But Paul lets the objector have his say as he usually does so that in verses 31-39 he considers the objections.

If God is for us, who is against us? (ε ο θεος υπερ ημων, τις καθ' ημων?). This condition of the first class carries Paul's challenge to all doubters. There is no one on a par with God. Note the two prepositions in contrast (υπερ, over, κατα, down or against).