For if ye love them which love you, what thank have ye? for sinners also love those that love them.

And if you love them that love you, what thanks are to you? for sinners also love those that love them.

and, if ye love those loving you, what grace have ye? for also the sinful love those loving them;

"If you love those who love you, what credit is it to you? Why, even bad men love those who love them.

And if you love those who love you, what credit is due to you? For even sinners love those who love them.

If you love only those who love you, what thanks will be due to you? Why, even the outcast love those who love them!

For sinners also love those that love them - I believe the word ἁμαρτωλοι is used by St. Luke in the same sense in which τελωναι, tax-gatherers, is used by St. Matthew, Matthew 5:46, Matthew 5:47, and signifies heathens; not only men who have no religion, but men who acknowledge none. The religion of Christ not only corrects the errors and reforms the disorders of the fallen nature of man, but raises it even above itself: it brings it near to God; and, by universal love, leads it to frame its conduct according to that of the Sovereign Being. "A man should tremble who finds nothing in his life besides the external part of religion, but what may be found in the life of a Turk or a heathen." The Gospel of the grace of God purifies and renews the heart, causing it to resemble that Christ through whom the grace came. See the note on Luke 7:37.

For if ye love them which love you, (g) what thank have ye? for sinners also love those that love them.
(g) What is there in this your work that is to be accounted of? For if you look to have reward by loving, seek those rewards which are indeed rewards: love your enemies, and so will you show to the world that you look for those rewards which come from God.

For if ye love them which love you, what thank have ye?.... Or, "what grace have ye?" this is no fruit, nor evidence of grace, nor any exercise of the true grace of love; nor is it any favour conferred upon the object loved, which deserves the respect shown, nor can any reward be expected for such treatment: and thus it is expressed in Matthew, "what reward have ye?" and the Arabic version renders it so here:
for sinners also love those who love them: men that are destitute of the grace of God, profligate sinners, even the worst of them, such as publicans, do this; See Gill on Matthew 5:46.

It is greatly observable, our Lord has so little regard for one of the highest instances of natural virtue, namely, the returning love for love, that he does not account it even to deserve thanks. For even sinners, saith he, do the same: men who do not regard God at all. Therefore he may do this, who has not taken one step in Christianity.