Remember that you were at that time separate from Christ, excluded from the commonwealth of Israel, and strangers to the covenants of promise, having no hope and without God in the world. Eph 2:12
Paul is speaking to the believing Gentiles who lived in Ephesus, in Asia Minor of the Roman Empire. He says that formerly, Gentiles had no hope in the world, because they are without God. They were without God, because they were strangers to the covenants of promise.
Now we have to remember that Paul is referring to the Old Testament when he is talking about these things, because in his day there were no other Scriptures. The Old Testament is the dictionary for the New. Every theological concept written about in the New, comes from the dictionary of the Old. To Jesus, the apostles, and Paul, the Old was the Scripture, the Word of God — we cannot forget that.
So we look into the Old to see what were the covenants of promise. Of course, these are the covenants God made with Abraham. Paul says “covenants,” because he is talking about more than just the Abrahamic covenant. The Abrahamic covenant was that God would multiply his descendants as the stars of heaven, and that God would be their God. Abraham had many sons – Ishmael, Isaac, and all the sons of Keturah. But the covenant of promise only went through Isaac, which God confirmed. Then Isaac had two sons – Esau and Jacob – but the covenant of promise only went through Jacob, which God confirmed. Jacob was renamed Israel, and all of Jacob’s sons partook of the covenant of promise. Not all Abraham’s sons were part of the covenant of promise. Not all Isaac’s sons were part of the covenant of promise. But all of Jacob’s sons became part of the covenant of promise, and were known as Israel. So when Paul says, covenants of promise, plural, he is talking about Abraham + Isaac + Jacob, plural, and not just Abraham, singular.
So the Gentiles were excluded from the covenants of promise, because they were not biologically descended from Israel, even if some of them might have been biologically descended from Abraham. The Gentiles were excluded from the commonwealth of Israel, therefore they were without God in the world. God did not make a covenant with anyone else that they would be His people and He would be their God, but only with Israel, did God made this covenant through Moses on Mt. Sinai.
What Paul is teaching us here, is that Israel is the door. The Old Testament teaches the same. When we were reading the Torah, remember how many times God said, that there would be one Torah for the native born and for the stranger who was with them? The stranger, who came to God, who dwelt with Israel, was to be as the native born.
Paul did not mistakenly use the word “stranger” here in Ephesians, when he said that the Gentiles were at one time strangers to the covenants of promise. Jesus told the woman at the well that the Samaritans worshiped what they did not know, while the Jews worshiped what they did know (God), because salvation is from the Jews (Joh 4:22).
Let us go even further back into the Old Testament. The grandsons and great-grandsons of Noah became the heads of the nations (Gen 10). But when the earth was divided and they were to go their places, in order to multiply and fill the earth, they rebelled against God and would not have Him be God over them, at the Tower of Babel. So God chose one man – Abraham – to be God of, and out of that one man, He made one nation and a people — His people. He woud be their God, and they would be His people.
But in that one man, all the nations of the earth would be blessed. God was making Abraham (or more specifically, Israel), like a doorway, through which the nations could return to Him, to become His people.
Now how do the Gentiles enter through the doorway of Israel to return to God? The prophets are very clear about this: through the Messiah of Israel. He will be a light to the Gentiles (Isa 9:6, Act 13:47). Jesus is the Door (Joh 10:7). It was God’s plan all along to have all the nations as His people, to be God of all the earth. But when the nations rejected Him from being their God, God made a Door through which their rebellion could be forgiven and they could be restored to Him. Though the door of Israel and Israel’s Messiah the Gentiles can be brought near to God — no longer be strangers — to be with God in the world.
But a random Gentile is without God in the world, if they are strangers to the covenants of promise, a non-participant in the commonwealth of Israel.
Continued in: Ephesians 2:15, the dividing wall