What does casting out Ishmael teach about the law and legalism?
Casting out Ishmael illustrates that believers must completely separate from the law and legalism in every form. Just as Ishmael was sent away, the law must be cast out because, from man's side, it is carnal, fleshly, and weak, though God's law is spiritual, perfect, and holy.
Les explains that casting out Ishmael, sending him into the wilderness so there was no contact between Isaac and Ishmael, is the lesson for dealing with the law and with legalism in all its hideous forms. The believer must be totally separated from it and cast it out. He notes that from man's side the law is carnal, fleshly, and weak, though from God's point of view it is spiritual, perfect, and holy. Paul writes in Galatians 4:9 that saved Gentiles were turning again to the weak and beggarly elements, desiring bondage—the law. Les also points to Romans 8:2-3 as saying practically the same thing.