Judaism is basically a religion only for Jewish people. Jews acknowledge most of Jewish law doesn't apply to outsiders, and that outsiders can still find favor with God without converting (law of Noah).
"Therefore we put our hope in You, Hashem our G-d, that we may soon see your mighty splendor, to remove detestable idolatry from the earth, and false gods will be utterly cut off, to perfect the universe through the Almighty's sovereignty. Then all humanity will call upon Your Name, to turn all the earth's wicked toward You. All the world's inhabitants will recognize and know that to You every knee should bend, every tongue should swear. Before You, Hashem, our G-d, they will bend every knee and cast themselves down and to the glory of Your Name they will render homage, and they will all accept upon themselves the yoke of Your kingship that You may reign over them soon and eternally."
This is to say -- Judaism is not entirely like "Judaism's for Jews, and everybody else can do whatever they like." At some point in the future non-Jews are supposed to recognize G-d as the Almighty too.
Out of curiosity, how does Judaism consider Christianity with respect to the phrase "remove detestable idolatry"? I happened across a debate about the New Testament's reliability in which the Orthodox Jew in the debate [Tovia Singer] argued that Christianity constituted idolatry and thus adherents violate the Noahide laws. I was pretty surprised by this, since my understanding was that most Jews do not hold this position.
