They apply to faith, to life according to faith, to receiving the mysteries, and to participation in all the sanctifying rites of the Church. The steadfastness and immovability must not be intermittent, as when one becomes zealous and then abandons it, begins again, and again abandons it.
It must be constant, unchanging, and even. “Always abounding in the work of the Lord.” What is this work of the Lord? The work of salvation. And in what does it consist?
“That you put off, concerning your former conduct, the old man, which grows corrupt according to deceitful lusts,” and “put on the new man, created according to God in righteousness and holiness of the truth” (Eph 4:22-24).
This is what Saint Chrysostom understands by the work of the Lord. He says that abounding is abounding “in a pure life.” The same thought is found in Theodoret: “Labor diligently to gather the wealth of piety.”
Doing the work of the Lord means doing every good thing. One must do good not somehow, not casually, but abound in doing it, “so that the good may be perfectly abundant and beyond the prescribed limits” (Saint Chrysostom).
“Knowing that your labor is not in vain in the Lord.” “This exhortation is just, for nothing so shakes steadfastness and immovability as the thought that one labors vainly and to no purpose” (Saint Chrysostom).
Therefore, he says, do not waver. Stand firmly in faith, in good deeds, and in patience on this path. The fruit of your labors is sure.
“The Judge is righteous and weaves crowns for the athletes (2 Tim 4:8). He has already prepared the wage for the laborers (Mt 20:8)” (Theodoret).
Whence comes this “knowing”? From what he said about the resurrection and the life to come. “In the Lord” suggests that all one’s labor must be directed in this way: it must be before the Lord.
It must be dedicated to Him and performed as though everything being done were done before the Lord’s eyes. Such labor is always free from every admixture of impure motives. It is always pleasing to the Lord.
He will not allow labor done for Him and before Him to be vain here, and still less there.
“Let us not, beloved, give ourselves over to sleep. It is impossible, utterly impossible, for the careless to be deemed worthy of the kingdom of heaven. The same is true of those given over to luxury and self-indulgence.
Rather, by exhausting and wearing down our body, and by enduring countless labors, we may receive the heavenly blessings. Do you not see how great the distance is between heaven and earth?
Do you not see what warfare lies before us, how inclined man is to evil, how sin surrounds us, and what snares it sets? Do you not know that what has been promised to you is beyond man?
Do you not know before what judgment seat we shall stand? Do you not remember that we must give account for words and thoughts?
Know that if we are careless, no one will defend us, neither righteous man, nor prophet, nor apostle. But if we are zealous, having sufficient defense in our own deeds, we shall with boldness be deemed worthy of the blessings prepared for those who love God” (Saint Chrysostom).