Since God revealed Himself to the Jews and their religion, what happened to all the Gentiles until Christianity was in effect. Does this mean that all Gentiles went to Hell, except the few Gentiles who believed in what the Jews preached?
Remember, in the beginning all mankind believed in God. Over time they drifted away from Him, so God called Abraham and through his descendants created a new race of people to show others the benefits that came from being in a relationship with God. After His people had been made into a nation and established in the Promised Land being in a relationship with God meant converting to Judaism.
The Jews always had a substantial missionary program, and by the time of Jesus there were thriving communities of converts all over the known world. In fact, the Court of the Gentiles was the largest part of the Temple.