You limit yourself to only Paul's writings, that is your business, not mine. Ephraim / the Gentiles is not the complete Body of Christ, Judah / the Jews is temporarily hardened, until the fulness of the Gentiles has come in, and in this way all Israel (Ephraim / the Gentiles and Judah / the Jews) will be saved. (Romans 11, I think it was Paul who wrote this, so maybe it applies to your limited view, of only Paul's writings applying to you.)
Romans 11 (ESV)
25 Lest you be wise in your own sight, I do not want you to be unaware of this mystery, brothers: a partial hardening has come upon Israel, until the fullness of the Gentiles has come in.
26 And in this way all Israel will be saved, as it is written, "The Deliverer will come from Zion, he will banish ungodliness from Jacob";
27 "and this will be my covenant with them when I take away their sins."