CLAIM: Isaiah writes, “Do not forgive them” (Isa. 2:9). How can we harmonize this statement with the NT teaching that we should “love our enemies and pray for those who persecute you” (Mt. 5:44; c.f. Col. 3:13)?
RESPONSE: We can solve this apparent dilemma by looking deeper into the original Hebrew language. Motyer writes, “The Hebrew imperative not only commands but is frequently used to express an inevitable result. In do not forgive them this idiom is used negatively. Isaiah is not commanding the Lord not to forgive but saying that forgiveness is unthinkable: ‘and for sure you will not forgive them.’” Moreover, this probably fits into Isaiah’s divine calling, where God explains to Isaiah that the people will not repent (Isa. 6:9-10). God—as an all-knowing being—knows who will and won’t turn to him in the future (Isa. 46:10).
 Motyer, J. A. The prophecy of Isaiah: An introduction & commentary. Downers Grove, IL: InterVarsity Press. 1996. Isaiah 2:9.