But now God's righteousness has been revealed apart from the Law, which is confirmed by the Law and the Prophets.
References for Romans 3:21
God's righteousness comes through the faithfulness of Jesus Christ for all who have faith in him. There's no distinction.
All have sinned and fall short of God's glory,
but all are treated as righteous freely by his grace because of a ransom that was paid by Christ Jesus.
Through his faithfulness, God displayed Jesus as the place of sacrifice where mercy is found by means of his blood. He did this to demonstrate his righteousness in passing over sins that happened before,
during the time of God's patient tolerance. He also did this to demonstrate that he is righteous in the present time, and to treat the one who has faith in Jesus as righteous.