The purpose of this verse is to indicate that God’s mercy is based on his own free choice and not on what men do. The verse is literally: “But if by grace, no longer from works, since the grace would no longer be grace.” In English the introductory words “but if” may convey the possibility of doubt. However, this is a form that in Greek introduces a condition true to fact, and so the verse need not be introduced by “if” (see Good News Translation, Moffatt, Jerusalem Bible).
The subject of the verse is not explicitly expressed, though it is clear from the context that it is his (God’s) choice, which most translations indicate by including a pronoun “it” (New English Bible “selected by the grace of God…. But if by grace, then it…”). It is obvious that the phrase “no longer on works” can be transformed to read not on what they have done. The second sentence in the Good News Translation again picks up the idea expressed in the first half of the verse (“but if by grace”), and so translates: For if God’s choice were based on what men do….
The clause his choice is based on his mercy may be rendered as “because he is so merciful, he selects as he does” or “God is so very merciful; therefore he selects as he does.” In this way one can show clearly the relation between the fact of God’s mercy as the basis for God’s selecting persons as he does. The connection with the latter part of the first sentence of verse 6 may then be explained as “he does not select people because of what they have done.”
In the second sentence of this verse, the word mercy is the same word used in the previous sentence.
There is some question regarding the force of the negative used in this sentence. The normal meaning is “no longer” (Revised Standard Version “otherwise grace would no longer be grace”; Moffatt, New English Bible “grace would cease to be grace”). If the negative is taken in this way, then the force of Paul’s argument would be as follows. Paul would be saying that God originally made this choice according to grace, but if he now changed the way that he worked and made his choice on the basis of what men do, then his choice would no longer continue to be made on the basis of grace. On the other hand, it is possible to take the negative to mean simply “not”: then his mercy would not be true mercy (An American Translation* “his mercy would not be mercy at all”; Jerusalem Bible “grace would not be grace at all”; New American Bible “grace would not be grace”). If this interpretation is followed, it means that Paul is not actually thinking in temporal terms, as we consider them; rather he is making the absolute statement that if God at any time had based his choice on what men do, then his mercy would not be true mercy.
In order to show clearly that what men do does not constitute the basis for God’s choice, one may translate as follows: “For if God were to choose people because they had done certain things, then he wouldn’t really be showing mercy” or “… the way in which he would be showing mercy would not be genuine.”
Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on Paul’s Letter to the Romans. (UBS Handbook Series). New York: UBS, 1973. For this and other handbooks for translators see here .