Why do Muslims claim Ishmael was the promised seed?

Muslims claim Ishmael was the promised seed because they argue the Old Testament has been polluted and distorted, rejecting its witness that the singular seed would come through Isaac, not Ishmael. Scripture affirms Isaac as the promised line through whom the Abrahamic covenant would continue.

Les teaches that the Abrahamic covenant promise ran through Abraham, Isaac, Jacob, and the twelve sons, ultimately bringing the Messiah. He notes that this line was not through Ishmael but through Isaac. The Muslim world argues against this, claiming the Old Testament has been polluted and distorted and that Ishmael was actually the promised seed. Les says this is how people are easily confused and led astray. But because the Bible is the Word of God, believers can rest on it that the singular seed would come through Isaac. In Galatians 3:16, the promises were made to Abraham and his seed, not many seeds but one seed, Isaac, and that seed is Christ. Thus all the world is blessed through this Abrahamic covenant.

Why do Muslims say Ishmael was the promised seed rather than Isaac?

Muslims argue that the Old Testament has been polluted and distorted, so they reject its testimony that the promise ran through Isaac. They claim that in reality Ishmael was the promised seed. The Bible, however, says the singular seed would come through Isaac, and that seed is Christ.