[This letter is from] Paul, a slave of Jesus Christ, [who was] called to be an apostle, [and] set apart for [preaching] the Gospel of God.

But now [i.e., under the Gospel age], a way of being considered right with God apart from [any] law has been made known. [The writings of] the law [i.e., the Pentateuch] and the prophets bear witness to this.

For we conclude that a person is made right with God by faith [in Christ], apart from [obedience to] the requirements of a law [or, the law of Moses, See verse 20].

But to the person who believes in God, who makes ungodly people right with Himself apart from doing good deeds, that person's faith is considered by God [as the basis] for being righteous.

Even King David also spoke of the blessing experienced by the person who was considered righteous by God apart from doing good deeds.