The firstborn here signifies the natural man, the old man in Adam. Since Adam was the first man (1 Cor. 15:45a), the firstborn includes everyone who is in Adam (cf. 1 Cor. 15:22a). The redeeming blood of Christ is not effective for those who remain in Adam (see note 1 John 2:22; cf. note Exo. 12:222). Furthermore, to apply Christ as the Passover in a complete and adequate way, we must condemn everything within us that is related to the firstborn, that is, to Adam (1 Cor. 5:6-8; Eph. 4:22).
