God made the New Covenant with the House of Israel and Judah (Jeremiah 31:31, et seq.; Hebrews 8:8, et seq.). Gentiles enter into the New Covenant by faith in Jesus, although Jewish people must place their faith in Him too for salvation and for the once and for all atonement for sins.
Agreed. I think it's just hard to say whether all Jews, or just some--as with the Gentiles--will eventually enter the New Covenant and be saved; I really can't even try to answer that one with my limited understanding of the Bible.