In Romans chapter one and two Paul has explained these things:

1. God has provided evidence to all men that there is a God, but men suppress this truth.
2. All men have God’s law written on their hearts, but this law accuses men when they fail to keep it.
3. Jews have God’s law written on tablets, but Jews cannot obey God’s commands.

So, by the time Paul gets to Romans 3:21 he has proven that all men are responsible to understand the knowledge of God and obey the law of God. All these men suppress the knowledge and disobey the law. This makes it impossible for God to justify any man. All men are condemned because they cannot meet the requirements of righteousness.

But, in Romans 3:21 Paul begins to explain the new revelation that was brought to light in his generation. God had revealed a righteousness that comes from God, not from man. Paul writes:

“But now apart form the law the righteousness of God has been made known.”

Paul says that even though this “righteousness from God” had just recently been revealed through Jesus Christ, “the Law and the Prophets testify” in agreement to this revelation.

This “righteousness from God” is given to the sinful, disobedient man who struggles in doubt and suppresses the truth “through faith in Jesus Christ.” Every man has fallen short of attaining righteousness by his own knowledge and deeds, but “all are justified freely” when they believe the promise of “grace through the redemption that came by Christ Jesus.”

"If lips and life do not agree, the testimony will not
amount to much."
- H. A. Ironside (1876-1951)