Here are some of the main themes and emphases of the gospel, according to Paul:-

1.  Its Power, Rom 1:16.  It brings salvation, deliverance, redemption, justification, etc.  See Rom 3:23f; 7:24f; 8:1; 1 Cor 15:1f; 2 Cor 5:18-21; 1 Tim 1:15.

2.  Its Author.  God in Christ is the author both of salvation itself and the gospel message which tells of that salvation, 1 Thess 2:9; 3:2.  The gospel is not man-made, Gal 1:11f; 2:16.  Man by nature is utterly incapable of saving himself, Eph 2:1,5,9.

3.  Its Emphasis.  The stress throughout is on sovereign, unmerited grace, Acts 20:24; Rom 3:23f; Eph 2:6-10; Tit 3:4-7.

4.  Its Message centres on the person and work of Jesus Christ, 1 Cor 15:1-11.

5.  Its Implication.  The sinner should appropriate this salvation, by repenting, 2 Cor 7:10; 2 Tim 2:25, and embracing Christ in faith, Rom 1:16f; Gal 3:11; Eph 2:8; Phil 2:12f.

6.  Its Ambassadors.  Paul and others had been set apart in a special way to proclaim this gospel, Rom 1:1; 1 Cor 9:16.  In a broader sense all believers are ambassadors of God’s grace.

7.  Its Appeal.  Since the gospel is so wonderful, and the need so great, there is an urgent appeal issued to men, 2 Cor 5:20.

Based on Hendriksen, New Testament Commentary on Philippians, 83-85.