The descendants of the one's God led our of Egypt. The people who Isaiah, Jeremiah, Ezekial, etc addressed.
Isa 1:1,
The vision of Isaiah the son of Amoz, which he saw concerning Judah and Jerusalem in the days of Uzziah, Jotham, Ahaz, [and] Hezekiah, kings of Judah.
Jer 2:2,
Go and cry in the ears of Jerusalem, saying, Thus saith the LORD; I remember thee, the kindness of thy youth, the love of thine espousals, when thou wentest after me in the wilderness, in a land [that was] not sown.
Ezek 2:3,
And he said unto me, Son of man, I send thee to the children of Israel, to a rebellious nation that hath rebelled against me: they and their fathers have transgressed against me, [even] unto this very day.
Neither Isaiah, Jeremiah, nor Ezekiel talked about the Christians church since the only one who did know about the church at that time was God, and He kept it to Himself until much later than these guys all wrote.