Originally Posted by Contra_Mundum

Now, depending on one's interpretation of how much God was revealing to Abraham about Ishmael's faith-condition, or eternal destiny, in Gen 17, God may have been telling him that Ishmael wasn't among the elect at all, but God was clearly telling Abraham Ishmael was neither the Elect (Christ) or his forebear). It is in this detail that God declares Isaac is the elect son, the one by whom the line of Messiah will be propagated.

Regardless, Ishmael was a party to the worldly administration of Abraham's covenant. "In that respect" he was in the covenant. He had a duty to find himself in the "tents of Isaac," and not chasing his own glory and ends. If he had, then he would have given us much more hope of his election in the one (Isaac) or One (Christ) with whom the covenant was made.