The purpose of this book is to communicate as clearly as possible Paul's gospel of God in its depth, from what I have learned over five decades of studying Paul's letters and theology. But, regardless of how much I have gained from teachers past and present, the bottom line is that "the things freely given us by God" in Paul's gospel can only be known by the Spirit of God, through comparing Paul's Spirit-taught words with Spirit-taught words (1 Cor 2:12-13). Luther's grasp of how justification in Christ—and thus faith in Christ—is central, is verified by what Paul says in Rom 1:16-17; that in the gospel, God's saving righteousness is revealed, from Christ's faith to our faith. The message of this book can be summed up as follows: The life of the person in Christ is to be one of trust in Christ for righteousness before God, and, through that faith, obedience to Christ as Lord. This life is possible because Christ believers have died with Christ to the lordship of the Sin and the law, and are alive to God in Christ Jesus—owned by him as Lord, being one spirit with him.