The Jews said to one another, “Where does this man intend to go that we cannot find him? Will he go where our people live scattered among the Greeks, and teach the Greeks?
The Jews cannot conceive that Jesus is talking of going back to the Father; they are completely puzzled. They venture sarcastically that maybe He will go to the Dispersion to teach the Greeks. The implication is that they themselves are much too smart for Him and have discovered the ruse He is trying to pull over on them, but the Greeks are much less learned in these spiritual things and maybe Jesus can convince those louts of His claims.
There were large numbers of Jews living in cities throughout the Roman Empire. Again, the opponents of Jesus have questioned whether He may be going to the Dispersion to teach, not the Dispersion, but the Greeks among whom they live. This would indicate a mission to the Greeks from the Jewish Synagogues in their towns, a method which is dismissed by these Jews as being a possibility for the Messiah to use. The irony is that this is the very method of evangelism used by the first Christian missionaries, as revealed later in the book of Acts. Jesus was indeed going to the Father but also to the Greeks, as His opponents are sarcastically accusing Him, through His missionaries.