 A castaway by definition is this, this is Webster's 1828, that which is thrown away. A person abandoned by God is unworthy of his favor, a reprobate, rejected, useless, of no value. Now, we are never cast off by God in the sense of losing salvation. If a person's saved, they're saved. They're kept by the power of the Lord Jesus Christ. So becoming a castaway is not losing your salvation.