We know that "the wages of sin is death" (Ro 6:23) because "the soul who sins will die" (Eze 18:4). It is a fact of life as Paul said he served "the law of sin which is in my members" (Ro 7:23). We are "sold into bondage to sin" (:14). You can yield yourself to serve "sin resulting in death" (6:16). When Adam and Eve sinned they were driven from the Garden of Eden (Ge 3:24) and lost their relationship with God. Consequently God developed a plan to reconcile humanity back to himself. However, there is the issue of the sin and guilt of humanity. The "curse of the Law" (Gal 3:13) convicts us and there is a "certificate of debt consisting of decrees against us" (Col 2:14). We are "delivered . . . into the power of our iniquities" (Isa 64:7). Job revealed that God would "'bring [man] into judgment with Yourself. Who can make the clean out of the unclean? No one'!" (Job 14:3-4). Furthermore, man cannot extradite himself "since by the works of the Law shall no flesh be justified" (Gal 2:16). That is why Jesus stated, "'The Son of Man has come to save that which was lost'" (Mt 18:11) and to rescue "those who are perishing" (2Co 4:3). "While we were still helpless, at the right time Christ died for the ungodly" (Ro 5:6). "While we were yet sinners, Christ died for us" (:8).
But God is just and his wrath must be appeased. "'I will not acquit the guilty'" (Ex 23:7). "He will by no means clear the guilty" (Nu 14:18). In other words, in his mercy he will not just unilaterally let humanity off the hook. "Do not enter into judgment with Your servant, for in Your sight no man living is righteous" (Ps 143:2). "If you, Lord, should mark iniquities, O Lord, who could stand?" (130:3). To acquit would be to pronounce a party not guilty. Therefore he must "be just and the justifier" (Ro 3:26). He is the one who "justifies the ungodly" (4:5). To be justified is a forensic term meaning to be justly treated or to be vindicated which is to exonerate. It is a judicial act whereby all the claims of the law are completely satisfied. It is a judicial process where the judges "justify the righteous and condemn the wicked" (Dt 25:1) which renders a verdict. "'Shall not the Judge of all the earth deal justly'?" (Ge 18:25). "The judgments of the Lord are true; they are righteous altogether" (19:9).