What did James understand about Paul's Gospel?
James understood that Paul's Gospel had been revealed and was primarily for the Gentile world, that God would call out a people for His name, and that it would be the Gentiles who would hear it, as the sovereign God who does all these things.
Les explains that this truth had never been mooted before, but now even James has a little bit of insight. Since Paul's Gospel has been revealed, and since it is primarily for the Gentile world, James recognizes that God is going to call out a people for His name. It is the Gentiles who will hear it, as verse 17 says: "...and all the Gentiles, upon whom my name is called, saith the Lord, who doeth all these things, known unto God are all his works, from the beginning of the age." Les points out that this shows the sovereign God is in control of everything, and nothing catches Him by surprise.