The gospel is Christ crucified for our sins and risen from the dead, according to the Scripture. The apostles in the New Testament preached Christ from prophecy in the Old Testament Scripture, and that includes the book of Psalms. Before the New Testament was completed, they preached the gospel of Christ according to the Scripture, which meant the Old Testament Scripture (1 Corinthians 15:1-4).
The gospel of Christ is throughout Old Testament prophecy, such as the Psalms. Christ is prophesied dying and rising again. Christ is prophesied coming the second time and reigning over all. Verses in the Psalms are quoted in the New Testament. Psalms reveal Christ in prophecy.
In Psalms we find the gospel of Christ. He is prophesied suffering death at the cross (Psalm 22). The Psalms also declare the resurrection of Christ (Psalm 16:8-11). That is the gospel of Jesus Christ foretold in the Psalms.
The Psalms prophesied the present day priestly ministry of our Lord Jesus Christ, as our Intercessor with God the Father (Psalm 110). Psalms also prophesied the second coming of Christ (Psalm 2).
The apostle Peter preached Christ and the resurrection on the Day of Pentecost from the book of Psalms (Psalm 16:8-11; Acts 2:25-28). That means the first gospel sermon in the Christian church was on Christ from prophecy in Psalms. Both the Old and New Testament reveal the gospel of Christ.
