Did God first promise Israel to all of Abraham’s descendants?

Question:       Did God first promise Israel to Abraham’s entire descendants, and then refine it to only through Isaac, or did he include both Ishmael and Isaac, or did he mean everyone and anyone who believed in Him that was a descendant of Abraham, meaning Jews, Muslims and Christians?

Answer:         The covenant was established for the descendants though Isaac only; Gen. 21:12 “…in Isaac shall my seed be called.” This is also confirmed in the New Testament; Rom. 9: 8 “…. the children of the promise are counted for the seed.”

There was a clause in the original covenant that allowed any and everyone that was willing to accept the terms of the covenant to become participants in the covenant; therefore Ishmael, Jews, Muslims, Gentiles, and Christians were included also. They weren’t born into the covenant; they have to literally accept it.