NOTES for Isa 66:18-21
It turns out that among the Lord's ways opening at this time there are also those that lead the saved on mission to other nations, to the Gentiles. We should not think, perhaps, that this prophecy has already been fulfilled; it continues to be fulfilled. The point is not that there are still peoples who have not received Christ's gospel. Rather, in every nation, in every city and village, there are still people consciously or unconsciously immersed in paganism; atheism is also one of its varieties. And in us ourselves there are more than enough remnants of paganism. Every time we decide something without even trying to compare our will with the will of God, every time we are guided by something other than love for someone else, we are true pagans. And we need to direct our mission to ourselves as well.
How important for successful mission is this sense that we and they are essentially one and the same, and only Christ is other. The universality of mission leads to the universality of the Church. How important for all of us is verse 21, pointing to universalism, to the supranational openness of the Church, to the absence in it of caste-like closedness.