In Romans 3:25b, Paul seems to answer an implicit objection about God’s relationship to sin. The question appears to be: If God is just, why has He overlooked so much sin in history? Even the Old Testament prophets sometimes cried out to God because of the surrounding injustice. For example, “How long, O LORD, must I call for help, but you do not listen?” (Habakkuk 1:2a). Habakkuk also asked, “Why do you make me look at injustice? Why do you tolerate wrong?”
The cross is God’s answer to such a question. The cross says, “God has now dealt with sin. Behold the sinless Son of God who bore the sin of the world.” In the cross God says, “I have not overlooked sin forever. I have not turned my back on evil. There was an appointed day and an Anointed One.”
Regarding the Father sending the Son as a sacrifice, Paul says, “He did this to demonstrate his justice” (Rom 3:25b). The word “justice” here means God’s “judging righteousness.” God has shown His wrath upon sin through the death of His Son who bore that sin. 2 Corinthians 5:21a teaches, “God made him who had no sin to be sin for us.”
The reason God had to demonstrate His judging righteousness in the cross was “because in his forbearance he had left the sins committed beforehand unpunished” (Rom 3:25b). Paul does not mean that God never punished sin. But in God’s prior punishments, it seems that Paul believed God’s punishments were not as all-encompassing as sin deserved. In that sense, some might want to charge God for ignoring sin. Paul says, No. God has shown once and for all what He thinks of sin. He has demonstrated His righteous character as Judge through Jesus’ substitutionary death.
God’s “forbearance” manifested in long-suffering and patience, in that the Creator (who was spurned and assaulted by human sin) did not punish mankind as we deserve. Now, because God has put forth His Son as a propitiation for sin, God commands all people to repent. People must turn from their sin and turn to God in adoration and worship. People must do this because God is righteous, just, holy, and amazingly merciful. Let us never presume on or cheapen such mercy. Today is the day of salvation (2 Cor 6:2).