Irenaeus

Among the other [truths] proclaimed by the apostle, there is also this one, "That flesh and blood cannot inherit the kingdom of God." This is [the passage] which is adduced by all the heretics in support of their folly, with an attempt to annoy us, and to point out that the handiwork of God is not saved. They do not take this fact into consideration, that there are three things out of which, as I have shown, the complete man is composed-flesh, soul, and spirit. One of these does indeed preserve and fashion [the man]-this is the spirit; while as to another it is united and formed-that is the flesh; then [comes] that which is between these two-that is the soul, which sometimes indeed, when it follows the spirit, is raised up by it, but sometimes it sympathizes with the flesh, and falls into carnal lusts. Those then, as many as they be, who have not that which saves and forms [us] into life [eternal], shall be, and shall be called, [mere] flesh and blood; for these are they who have not the Spirit of God in themselves. Wherefore men of this stamp are spoken of by the Lord as "dead;" for, says He, "Let the dead bury their dead," because they have not the Spirit which quickens man.

This truth, therefore, [he declares], in order that we may not reject the engrafting of the Spirit while pampering the flesh. "But thou, being a wild olive-tree," he says, "hast been grafted into the good olive-tree, and been made a partaker of the fatness of the olive-tree." As, therefore, when the wild olive has been engrafted, if it remain in its former condition, viz., a wild olive, it is "cut off, and cast into the fire;" but if it takes kindly to the graft, and is changed into the good olive-tree, it becomes a fruit-bearing olive, planted, as it were, in a king's park (paradiso): so likewise men, if they do truly progress by faith towards better things, and receive the Spirit of God, and bring forth the fruit thereof, shall be spiritual, as being planted in the paradise of God. But if they cast out the Spirit, and remain in their former condition, desirous of being of the flesh rather than of the Spirit, then it is very justly said with regard to men of this stamp, "That flesh and blood shall not inherit the kingdom of God;" just as if any one were to say that the wild olive is not received into the paradise of God. Admirably therefore does the apostle exhibit our nature, and God's universal appointment, in his discourse about flesh and blood and the wild olive. For as the good olive, if neglected for a certain time, if left to grow wild and to run to wood, does itself become a wild olive; or again, if the wild olive be carefully tended and grafted, it naturally reverts to its former fruit-bearing condition: so men also, when they become careless, and bring forth for fruit the lusts of the flesh like woody produce, are rendered, by their own fault, unfruitful in righteousness. For when men sleep, the enemy sows the material of tares; and for this cause did the Lord command His disciples to be on the watch. And again, those persons who are not bringing forth the fruits of righteousness, and are, as it were, covered over and lost among brambles, if they use diligence, and receive the word of God as a graft, arrive at the pristine nature of man-that which was created after the image and likeness of God.

But as the engrafted wild olive does not certainly lose the substance of its wood, but changes the quality of its fruit, and receives another name, being now not a wild olive, but a fruit-bearing olive, and is called so; so also, when man is grafted in by faith and receives the Spirit of God, he certainly does not lose the substance of flesh, but changes the quality of the fruit [brought forth, i.e., ] of his works, and receives another name, showing that he has become changed for the better, being now not [mere] flesh and blood, but a spiritual man, and is called such. Then, again, as the wild olive, if it be not grafted in, remains useless to its lord because of its woody quality, and is cut down as a tree bearing no fruit, and cast into the fire; so also man, if he does not receive through faith the engrafting of the Spirit, remains in his old condition, and being [mere] flesh and blood, he cannot inherit the kingdom of God. Rightly therefore does the apostle declare, "Flesh and blood cannot inherit the kingdom of God;" and, "Those who are in the flesh cannot please God:" not repudiating [by these words] the substance of flesh, but showing that into it the Spirit must be infused.