“We know that the Old Testament is as much God’s word as the New Testament. Christ, in referring to an Old Testament scripture, said scripture cannot be broken (John 10:34-35). Paul wrote, “All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness” (2 Timothy 3:16).
How can we reconcile the harshness of some of the Psalms with the mercy taught in the New Testament?
Both are true and right teachings, and both reflect the mind of God. David is called a man after God’s heart (1 Samuel 13:13-14, Acts 13:22).”
Editor: The quotations above are from a post entitled “David’s Prayers for Vengeance” located here:
use this link to read the full blog post it is very enlightening.