Ok, I see (and agree with) what you were saying about it referring to the Jews (as opposed to the Gentiles he is writing to. So you are saying then, that only the Jews were predestined? I don't see how that follows, logically.
What I'm saying is that that passage in Ephesians 1 is talking about the Jews. But, yes the Jews were predestined, the Gentiles weren't. When Paul speaks of the Jews being adopted He's referring back to promises that God made to Abraham. God told Abraham that he would be the father of a great nation and that he would receive all of the land that he could see. He promised the land to Abraham and his seed. Right there Israel was predetermined or predestined. Paul said in Romans that the adoption pertains to the Jews.
4
Who are Israelites;
to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and
the promises;1
5
Whose are the fathers, and of whom as concerning the flesh Christ came, who is over all, God blessed for ever. Amen. (Rom. 9:4-5 KJV)
The word pertains isn't in the Greek text. It literally says, 'who are Israelites; to whom the adoption.' God did adopt Israel.
22 And thou shalt say unto Pharaoh, Thus saith the LORD,
Israel is my son, even my firstborn: (Exod. 4:22 KJV)
This is what Paul is talking about. The Gentiles weren't predestined, it was Israel. The Gentiles can become a part of the promises by becoming a part of Israel. Paul said in Romans 11 that the Gentiles have been grafted into the olive tree. Here he turns his attention from the Jews to the Gentiles and begins his address to the Gentiles.
13
For I speak to you Gentiles, inasmuch as I am the apostle of the Gentiles, I magnify mine office:
14 If by any means I may provoke to emulation them which are my flesh, and might save some of them.
15 For if the casting away of them be the reconciling of the world, what shall the receiving of them be, but life from the dead?
16
For if the firstfruit be holy, the lump is also holy: and
if the root be holy, so are the branches.
17 And if some of the branches be broken off, and
thou, being a wild olive tree, wert graffed in among them, and with them partakest of the root and fatness of the olive tree;1
18 Boast not against the branches. But if thou boast, thou bearest not the root, but the root thee.
19 Thou wilt say then, The branches were broken off, that I might be graffed in.
20 Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear:
21 For if God spared not the natural branches, take heed lest he also spare not thee. (Rom. 11:13-21 KJV)
So, here Paul is telling the Gentile believers in the church at Rome that they have been grafted in. They've been grafted into Israel. In Galatians Paul tells the Galatians that if they are in Christ they are Abraham's seed and heirs according to the Promise.
29 And
if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise. (Gal. 3:29 KJV)