In this lies quickening by the spirit, which from the beginning became the goal of life. The Apostle means not believers only, but all men living at every time. All must live for the one Lord.
If they do not live this way, it is their fault. To what extent ignorance excuses anyone, God will judge. Yet the law is unalterable: after the Lord died for all and rose, all must live for Him.
This is the norm of human life. We possess this temporal life, with the means of quickening the spirit, because the Lord died for all.
After death, while we remain separated from the body, we shall live in hope of the resurrection in an incorrupt body because He rose in our nature.
If, then, everything essential in our life is from Him, the law of righteousness commands us no longer to live for ourselves, but for Him alone.
Chrysostom says: "The Apostle said that we must not live for ourselves, and he presents the evident reason why we must act so. If we live by Him Who died for us, then we must also live for Him by Whom we live.
"Although what he said seems to contain one reason, if we examine it carefully, we shall find two. The first is that we live only by the Lord. The second is that He died for us.
"Each of these, taken separately, is sufficient to make us obedient to Him. How much more indebted to Him we must be when we join both together.
"Yet a third reason is hidden in his words. For your sake the Lord raised and carried up to heaven the firstfruits of our nature. Therefore he added: 'Who died for us and rose again.'"
What is required by the obligation to live not for oneself the Lord defined thus: "If anyone would come after Me, let him deny himself, take up his cross, and follow Me."
What is required by the obligation to live for the Lord, the Lord said in these words: "He who loves Me keeps My commandments." Blessed Theodoret writes: "We acknowledge it just to live for Him and to conduct life according to His commandments, because our debt to Him obliges us to this."
Yet such requirements are plainly fulfilled only by those who have come to know the Lord, believed in Him, and cleaved to Him with their whole soul. Therefore, although the Apostle said that all who live are obligated to live not for themselves but for the Lord, he spoke according to the idea.
His intention was especially to fix the attention of believers on this point, first those to whom he wrote, and then all believers. For if all men are obligated to this, believers are obligated all the more.
They have accepted the obligations and have also received the strength to fulfill them in the grace of the Holy Spirit. Believers in the Lord, when they come to Him, renounce impiety and worldly desires.
At first they do this in intention, desire, and resolve of will. Yet when they are reborn to new life in the font of baptism, they receive grace-filled power.
This power actually frees them from impiety and desires, and directs them toward a chaste, righteous, and pious life. Thus, not living for oneself, that is, not according to the selfish impulses of the flesh, belongs inseparably to true believing Christians.
Living for the Lord, that is, according to His holy, pleasing, and righteous will, also belongs to them inseparably. In relation to them the Apostle's word means this.
This is how it must be, and it cannot be otherwise, if you are what you ought to be.