What is a Jew? Rabbi Morris N. Kertzer
Jews regard Judaism as the only religion for Jews - both those born Jewish and those who choose to become Jews through conversion.  But we respect the honest, devout worshiper of any faith.  The Rabbis held, "The righteous of all nations have a share in the world to come."
The rabbinic metaphor is a covenant, by which we mean an agreement freely entered into between G-d and various religious communities.  The Jewish covenant is the one made at Sinai, when Jews agreed to observe the Torah.  But G-d makes covenants with other peoples also.  The Rabbis called them Noachide covenants, meaning the kind of covenant G-d made with Noach, who was not Jewish.  According to the terms of the Noachide covenants, non Jewish religions are held responsible for recognizing the one true G-d and turning away from idolatry, for establishing systems of justice in their midst, and for maintaining basic moral virtues.
It is the recognition of the reality of G-d, and the basic moral virtues, wuch as kindliness, justice, and integrity, that we regard as eternal verities.  But we claim no monopoly on these verities, for we recognize that every great religious faith has discovered them.  That is what Rabbi Meir meant some eighteen centuries ago, when he said that a non-Jew who follows the Torah is a good as our high priest.  There are many paths to the One G-d.