Originally Posted by Contra_Mundum

I think it is simpler to just say that God will wait until all his elect are brought in, and completes any other purpose of his for the world (which is subordinate in any case, and surely tied in both time and effect closely to the main). And then everything shudders to a halt for Judgment Day.

Rev 5:9 And they sing a new song, saying, Worthy art thou to take the book, and to open the seals thereof: for thou was slain, and didst purchase unto God with thy blood men of every tribe, and tongue, and people, and nation."

Some languages have come and gone. Perhaps without a single convert. But the passage is teaching a fullness of the redemption. Everyone on this earth, whatever their language pattern, is ultimately related, so back up far enough and they are "one" with somebody else in identity and language.

Bottom line: I don't think God is waiting for us to "close the 10-40 window," as much as he is expecting us to simply preach the gospel as wide and far as humanly posible.