Judaism has never been a sectarian religion of the Jews

Isaiah 56:3-8 KJ3

(3) And do not let the son of the alien speak, he who joins himself to Jehovah, saying, Separating Jehovah separates me from His people; and not do let the eunuch say, Behold, I am a dried up tree.

(4) For so says Jehovah to the eunuchs who keep My sabbaths and choose things I am pleased with, and take hold of My covenant:

(5) I, even I will give to them in My house and in My walls a hand and a name better than sons and than daughters; I will give them an everlasting name which shall not be cut off.

(6) And the sons of the alien who join themselves on Jehovah to serve Him, and to love the name of Jehovah, to be His servants, every one who keeps from defiling the sabbath, and takes hold of My covenant,

(7) and I will bring them to My holy mount and make them joyful in My house of prayer. Their burnt offerings and their sacrifices shall be for acceptance on My altar, for My house shall be called a house of prayer for all the peoples,

(8) a statement of the Lord Jehovah, who gathers the outcasts of Israel; I will yet gather to him his gathered ones.