"Justification by the grace of God through the faithfulness of Jesus for all who share in his faith."
(Yung Suk Kim, based on Rom 3:21-26)
I wrote extensively about Paul's theology, featuring the threefold gospel, where three elements are essential: God's righteousness, Jesus's faithfulness, and Christian participation in the faith of Jesus.
For example, see my recent publication, How to Read Paul (Fortress, 2021).
The more I teach, the more I am convinced about this.