1 Corinthians 15:14

14. Our preaching… your faith Our preaching and your faith are alike a vanity. St. Paul does not suppose that any one will reply. But even without a resurrection, is not the soul immortal, and may not its immortality be blissful through Christ? He does not anticipate this reply, because those deniers did not admit any such immortality. Nor, to all appearance, does Paul himself base our Christian hopes upon an immortality of soul that is not based on Christ, that is, of which our resurrection is not the base, and that based on his resurrection. He preached not Jesus and the immortality of the soul, but Jesus and the resurrection. That he believed in the separate existence and immortality of the soul appears from Philippians 1:23-24. But man is an immortal being, not because he is a thinking substance, for brutes think; but because he is by God placed in the conditions for immortality. A lamp will burn forever if the conditions of carbon and oxygen are properly supplied. An animal would be immortal if placed by God in the conditions for its immortality. Now man is an immortal being because he is placed by God in a probationary system, the basis of which is the resurrection, the accompaniment of which resurrection is the perpetuation of the existence of the soul through the intermediate state until its reunion with the body. Of this destiny for immortality, the proofs drawn from the high intuitive character of the spirit of man are valid and powerful. Animals fear death, and avoid localities of danger. But animals are below the conception of immortality, which is a form of the idea of the Infinite.

From this view it is clear that no argument can be drawn against the immortality of man from the high intellective character of some animals. We are not, indeed, obliged by Christianity to deny the immortality of brutes, or insects. We are perfectly free to believe even that every case of individualized perceptive life, (that is, every intellective entity individualized by being once united to a material organism,) remains a thinking individual forever. But the Pauline ground for man’s immortality is the assumed fact of man’s probationary condition under the headship of Christ, as heir of the resurrection.