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 Cor. 15:1-4).
Prophecy reveals the gospel of Christ in the Psalms. We see Christ dying and rising again. We see Christ coming the second time and reigning over all. Verses in the Psalms are quoted in the New Testament. Psalms revealed Christ in prophecy.
The Psalms prophesied Christ suffering death at the cross (Psalm 22). Psalms also declared the resurrection of Christ (Psalm 16:8-11). That is the gospel of Jesus Christ foretold in the Psalms.
The book of 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.
