He deserved to die and to be cut off from fellowship with God. But David repents and pleads for covenant mercy. Isaiah describes Israel's deliverance from Babylon and her restoration to divine favor and privileges as an act of divine justice. Isaiah 40 to 66 is mostly one inspired celebration of God's righteousness, which means salvation for His oppressed people. But he does it in the light of God's final and ultimate act of salvation, which has taken place in the death and resurrection of Christ.
Biblical theology is covenant theology.
Because it grounds man's salvation on God's justice, it gives an absolutely solid basis for a man's faith. While he may be tempted to think that God's mercy may run out, his own conscience tells him that God will be just. Unrighteousness Unrighteousness or sin means failing to do what is expected as a covenant partner. Sin is an act of in-fidelity and unfaithfulness to the covenant responsibility. The Westminster Confession, therefore, is quite right and biblically concrete when it defines sin as any lack of conformity to the law of God.