Having spoken about God’s sovereignty in salvation and emphasizing that salvation — for both Jew and Gentile — is a gift of God’s unmerited mercy, Paul now shifts our focus to the choice that stands before us — What will we do with Jesus. The righteousness that we need is a gift received through faith in Jesus and is not something we can achieve by our own striving and efforts. If we trust Jesus, he will be the foundation stone upon which our lives will stand, but if we aim to achieve righteousness by our performance, he will prove to be the stumbling stone over which we trip.
