God worked with Israel to eventually launch the mission. You might say it started by getting Abraham out of Asia to the place where all 3 continents converge, so that when people went home from Pentecost, they went to every nation under heaven.
The gospel was announced in advance to Abraham: All nations will be blessed through you, and he (God) was referring to justification by faith, Gal 3:8, the official interp of the Genesis promise. It was about justification by faith in Christ. That's why Acts 13's sermon says the same thing. All of the promises have been fulfilled in the resurrection. The resurrection being the proof that there is justification from sins.
Galatians 3:8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed.
You make the same mistake on that passage as the Acts 28ers within Dispensationalism.
That passage is not focusing on what was preached unto Abraham.
Rather, on the fact that Abraham believed what had been preached unto him way back then.
He only mentions it because he is pointing out to these Law bound Galatians that the very father of the circumcision who now have them in bondage under the Law; Abraham himself: had operated on the principle of faith alone, that day, way back when.
It is asserting the exact same principle that Paul has been preaching all along, and that he will reiterate some ten years or so later, in Romans 4.
Galatians 3:5 He therefore that ministereth to you the Spirit, and worketh miracles among you, doeth he it by the works of the law, or by
the hearing of faith? 3:6 Even as Abraham believed God, and it was accounted to him for righteousness. 3:7 Know ye therefore that they which are of faith, the same are the children of Abraham. 3:8 And the scripture, foreseeing that God would justify the heathen through faith, preached before the gospel unto Abraham, saying, In thee shall all nations be blessed. 3:9
So then they which be of faith are blessed with faithful Abraham. 3:10 For as many as are of the works of the law are under the curse: for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them. 3:11 But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith.
Verse 8 is actually a repetition, in a sense, of the principle mentioned in verse 6.
Verse 6 is the principle and verse 8 is the context in which Abraham had operated under said principle.
Sort of like saying "You know how back when God said such and so to Abraham, and he believed Him, so God counted His faith for righteousness - well it's the same principle....
3:6 Even as Abraham believed God, and it was accounted to him for righteousness. 3:7 Know ye therefore that they which are of faith, the same are the children of Abraham.
Paul will later summarize all that...
Galatians 5:1 Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage. 5:2 Behold, I Paul say unto you, that if ye be circumcised, Christ shall profit you nothing. 5:3 For I testify again to every man that is circumcised, that he is a debtor to do the whole law. 5:4 Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace. 5:5 For we through the Spirit wait for the hope of righteousness by faith.
That last passage is UNDERSTOOD as "For we through what the Spirit has accomplished from the very moment in which we believed Christ died for our sins, wait or confidently rest in the hope that is now ours as a result - the righteousness which is now ours by faith, or from the very moment in which we believed.
Note..
Galatians 3:1 O foolish Galatians, who hath bewitched you, that ye should not obey the truth, before whose eyes Jesus Christ hath been evidently set forth, crucified among you? 3:2 This only would I learn of you, Received ye the Spirit by the works of the law, or by the hearing of faith? 3:3 Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh? 3:4 Have ye suffered so many things in vain? if it be yet in vain. 3:5 He therefore that ministereth to you the Spirit, and worketh miracles among you, doeth he it by the works of the law, or by the hearing of faith? 3:6 Even as Abraham believed God, and it was accounted to him for righteousness.
Nope, IP, you can keep your notion that Abraham had believed this as some sort of a "one size fits all" the same exact, good news, across the board.
Acts 17:11,12.
