From Faith for Faith

16 For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek. 17 For in it the righteousness of God is revealed from faith for faith, as it is written, “The righteous shall live by faith.” Ro 1:16-17

Looking at verse 17 and again gaining insite from John Piper's sermons on Romans, Paul says the righteousness of God is revealed in it (the gospel) from faith (our faith). The righteousness of God is credited to us by God resulting from God's grace to us in our faith in him. Righteousness is established in faith and this empowers our persistence in faith (ie from faith to faith). Paul quoting Habakkuk 2:4 finishes verse 17 with the words, "the righteous shall live by faith." There are two possible interpretations for this ending. Both I believe are true, but the latter makes the most sense in context. The first is that we will live our lives here on earth by faith. So, as Paul says in Galatians..."the life I live in the body, I live by faith in the son of God, who loved me and gave himself for me (Gal 2:20)" We are sustained and energized for life in faith. The second interpretaion is that the word "live" refers to eternal life in glory. We receive eternal life in heaven by faith. Piper discusses Romans 1:17 as being the verse that transformed Martin Luther as he realized the meaning and significance of Paul's words.

Observations:
1) The gospel reveals the crediting of righteousness to those who believe.
2) Faith is the "vehicle" through which righteousness is applied.
3) God is the power by which we receive righteousness.
4) Eternal life is the result of faith.
5) By inference, works are not necessary for imputed righteousness and eternal life.