There are many different kinds of nations in the world and we see that most of the world does not know anything about the Torah. The fact that there are Jews and non-Jews is a consequence of Adam's sin, which means that originally G-d never had the intention to divide mankind between Jews and non-Jews. It was the purpose of Adam to reach the World to Come through performing a single mitzvah and Adam failed. This failure was continued on to his descendants. They too failed, and therefore his descendants were separated into two different groups - those who failed, the eventual non-Jews; and then there was Avraham. Avraham and his descendants retained the goal of the World to Come. Yet it was only after all the nations refused the Torah that they were eventually cut off from the World to Come.