John Chrysostom
"Therefore we are zealous, whether dwelling or departing, to be pleasing to Him" (v. 9). "Whether we are there or here," he says, "our work is only to care for living according to His will, because this is our chief duty. Thus, with this pleasing of God, you are undoubtedly an heir of the kingdom."
But lest the believers, having acquired such a passionate desire to depart to the Lord, should grieve over the delay of this departure, the Apostle here already gives them what is chief among all blessings. What is it? To be pleasing to the Lord.
It is not simply good to depart from here, but to depart after having pleased Him. Through this latter thing, the former becomes good. Likewise, it is not simply grievous to live here, but grievous to live while offending God.
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Therefore do not think that for eternal life mere separation from the body is enough. Virtue is needed everywhere. Thus, when speaking about the resurrection, he did not give grounds to rely on it alone, saying, "provided that when clothed we shall not be found naked."
So too, when speaking about separation from the body, lest you think this alone is sufficient for salvation, he added that one must also be pleasing to God.
Having thus stirred their zeal by manifold blessings, the Apostle did not forget to move them also by fear of threatening evils. For our blessedness consists both in acquiring blessings, that is, the heavenly kingdom, and in avoiding evils, that is, Gehenna.
Yet the desire to escape torments has a stronger effect. If the harm were limited only to deprivation of eternal blessings, many would easily agree to it. But if it is joined to torments, hardly anyone would agree.
Of course, the former should be considered more unbearable. But for many, because of their weakness and attachment to earthly things, the latter appears more grievous.