This recalls 2.19-20. For doing good, see 2.12 and 2.15; and for doing evil, see 2.12 and 2.14, where the nominal form of the verb appears. If this should be God’s will is in the optative mood, for which see the various possibilities discussed in verse 14. God’s will in this case may be to suffer for doing good (as in Good News Translation, New English Bible, Die Bibel im heutigen Deutsch, Moffatt, Knox) or simply “suffering” (for example, New American Bible “If it should be God’s will that you suffer, it is better to do so for good deeds than for evil ones”; also Phillips, Jerusalem Bible). Both are possible, although the Greek construction lends weight to the former.
The interruption of the comparative expression in verse 17 by the conditional clause if this should be God’s will causes certain complications in a number of languages. It may therefore be necessary to translate “for it is better to suffer for having done good than for having done what is bad, if indeed it is God’s will that you should suffer.” The conditional expression may also be expressed as a potential event, “… for it might be that it is God’s will for you to suffer” or “… since it might be that your suffering is what God has decided should be.”
Quoted with permission from Arichea, Daniel C. and Nida, Eugene A. A Handbook on The First Letter from Peter. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .