Their seed shall be known among the Gentiles i.e. eminently; a promise of the increase of the church; such shall be their prosperity and multiplying, that they shall be known abroad by their great increase. Or else the meaning is, The church shall have a seed of the Gentiles, the borders of the church shall be enlarged; whereas it hath been confined as it were to one corner of the world, now it shall remain in one nation alone no more, but shall fill all the nations of the earth. They are the seed which the Lord hath blessed; they shall be known to be the seed of Abraham, partly by their holy conversation, and partly by their exceeding blessings, it being the seed that the Lord had so often promised to bless. There shall be such visible characters of God's love to them, and of God's grace in them.
Related Commentaries of Isaiah 61:9
Isaiah 61:9
9 And their seed shall be known among the Gentiles, and their offspring among the people: all that see them shall acknowledge them, that they are the seed which the LORD hath blessed.