Though the Greek expressions is this verse are not imperatives, they are used to express obligation and should be so translated in English.

It is very difficult in some languages to say love must be completely sincere. One can speak of people as “loving sincerely” but not of “love being sincere.” Hence one may say “when you love you must be completely sincere” or “you must be completely sincere in your loving people.” Moreover, it is not easy in some languages to find a term for sincere. In some languages a negative expression is employed—for example, “don’t pretend to love.”

Hold on to what is good may be rendered idiomatically as “tie yourself to what is good.” Since hold on to is in contrast with hate, it may be useful to suggest something of the emotive implications involved—for example, “hold on to in your heart” or “keep firm in your heart.”

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 .