John Calvin Commentary Acts 15:17

"That the residue of men may seek after the Lord, And all the Gentiles, upon whom my name is called," — Acts 15:17 (ASV)

That those which remain may seek. James added this word seek by way of exposition, which is neither found nor read in the prophet; and yet it is not superfluous, because, so that we may be numbered among the people of God, and that he may take us as his own, we must, in turn, be encouraged to seek him.

And it is thought that Luke summarily comprehended those things about which James disputed in his own language among the Jews; by which it happened that the exposition of the matter was mixed with the words of the prophet. Instead of the relics of the Gentiles which Amos uses, Luke, from the Greek translation (which was more familiar), puts the rest of the men in the same sense, namely, that a cutting, or paring, must precede the purging of the world's filthiness, as happened.

And this doctrine must also be applied to our time. For, because the world's corruption is so great that it cannot be wholly brought to obey Christ, he blows away, with diverse fans of tribulations, the chaff and weeds, so that he may at last gather to himself that which will remain.