What accords with the foundation is durable. What does not accord with it is unstable. The foundation itself is so firm that it can neither be moved nor replaced. Therefore everything in harmony with it will also be firm and durable.
But first we must define what is meant by building upon it. Is it the teaching of teachers, or the life of each Christian? According to the Apostle’s purpose, it would be nearer to understand the teaching of teachers.
Yet since he speaks generally, it is not surprising if he meant to suggest both. He addresses teachers, that they should teach soundly. He addresses every Christian, that he should live as he ought.
Theodoret writes: “Some maintain that the Apostle says this about dogmas. But I think that he says it about active virtue.” Thus in his time opinions were divided.
Under the words, “Let each one take heed how he builds,” Chrysostom said: “Here, it seems to me, he turns them toward the struggles of life.”
But afterward, explaining the meaning of the foundation that had been laid, he says: “The Apostle’s words mean this. I proclaimed Christ and gave you the foundation. See how you build upon it. Is it with the aim of turning disciples away from Him and drawing them to certain men? Let us not be carried away by heresies.”
From this it is clear that Chrysostom understood building to mean both the teaching and the teachers, and the life of the faithful. Although afterward he speaks chiefly about the latter, this was required by the purpose of his homilies, which are always moral.
What teaching, then, is durable? It is teaching that develops directly from the foundation laid and is established upon it.
That is, teachers strive to explain to their disciples only how salvation was arranged and how one is saved. They teach how God created us and placed us in Paradise. They teach how we fell.
They teach how the merciful God did not abandon us in our fall, but graciously willed to arrange salvation for us. He did not spare His only-begotten Son.
They teach how the Son of God came to earth, was incarnate, suffered, and died on the Cross for our salvation. They teach how afterward He rose, ascended into heaven, and sent down the Holy Spirit to arrange the salvation of each person.
They teach how these persons are called to salvation by the grace of God. They are mystically made partakers of the Lord’s death. Having received new life, they are led toward perfection through voluntary and involuntary deprivations and sorrows.
Through death they are conveyed into the realm where blessedness with the Lord begins beforehand.
Whoever teaches all this, and teaches it as it is portrayed in the New Testament, prefigured in the Old, explained by the holy Fathers, and maintained by the holy Church, teaches soundly.
If he teaches simply and intelligibly, with the one aim of building up the souls of his hearers, then his teaching is durable, like gold, silver, and precious stones.
But another may teach without violating the dogmas, yet speaks only about side matters. These merely fill the head and awaken a proud opinion of learning in him and in those who listen to him.
Or a man may teach the matters of faith more according to rational considerations than as they have been handed down in revelation. He then acts as though they receive their force precisely from these considerations.
Or one may teach about the Christian life while striving in every way to conceal its obligatory severity. Instead of the Cross, he introduces self-pleasing and comfort, and so makes the Cross of Christ of no effect.
Whoever teaches in this way, or in a similar way, has unstable teaching. It is hay, reed, and brushwood. The discussions of the Corinthian parties belong here also. They were petty, the fruit of frivolity and idleness.
Whose life is durable? The life of one who has been mystically united to the death of Christ and has received new life in Christ.
Strengthened in his heart by the grace of the Holy Spirit, he knows how to enter more and more deeply into being crucified with the Lord.
He indulges self-pleasing in nothing. He constantly crucifies the flesh with its passions and desires. He is ready to die sooner than indulge himself in anything, or violate even the smallest commandment that he recognizes.
He does all this not from any fear, but from love for the crucified Lord, who by His death bestowed life upon us. Whoever is so disposed has rules of life and works that are gold, silver, and precious stones.
But a man may not openly violate the commandments and may lead an orderly life. Yet he has no concern to keep his heart pure for the Lord.
For this reason he does not struggle with himself. He does not keep himself in works of self-denial as an aid to that struggle.
Therefore he denies himself none of the comforts and pleasures possible on earth, which the spirit of this age has introduced into the order of life.
He does not count them contrary to the Cross of Christ, which every Christian is obliged to bear. Such a man’s rules of life and works are unstable. They are hay, reed, and brushwood.
It should be noted that in this half of the admonition, 1 Cor 3:10-15, the Apostle contrasts sound teaching and truly Christian life with something else.
He does not oppose to them false teachers and manifest sinners. Rather, he speaks of teachers who hold to the foundation laid and labor on this foundation to raise the building of teaching.
Only they take unstable material: learning that has no relation to the matter, and the like. He also speaks of Christians who do not wish to destroy their soul, but imagine that they are saving it.
For this they do convenient works. That is, they also raise the building of salvation, yet they refuse to deny themselves anything. Their material is hay and reed.