John Calvin Commentary Isaiah 51:6

"Lift up your eyes to the heavens, and look upon the earth beneath; for the heavens shall vanish away like smoke, and the earth shall wax old like a garment; and they that dwell therein shall die in like manner: but my salvation shall be for ever, and my righteousness shall not be abolished." — Isaiah 51:6 (ASV)

Lift up your eyes toward heaven. When we see so great changes in the world, we are apt to think that the Church comes within the influence of the same violent motion. Therefore, we need to have our minds elevated above the ordinary course of nature; otherwise, the salvation of the Church will appear to hang on a thread and to be carried to and fro by the billows and tempests.

Yet, we can see both in heaven and on earth how wisely God regulates all things, with what fatherly kindness He upholds and defends His workmanship and the frame of the world, and with what equity He provides for all His creatures. But in a remarkable manner, He deigns to watch over His Church, since He has separated her from the ordinary rank.

And look upon the earth beneath. Both of these views are embraced here by the Prophet, for he instructs believers to turn their eyes upwards and downwards, so as to perceive both in heaven and on earth the wonderful providence of God, by which He so beautifully preserves the order and harmony that He first established.

But he adds that, though heaven and earth hasten to decay, it is impossible for the Church to fail, whose stability is founded on God. It is as if he had said, “A thousand times sooner would heaven mingle with the earth than the promise on which your salvation rests would fail to be fulfilled.”

My salvation shall endure for ever. First of all, he mentions salvation, and next he speaks of righteousness, on which it rests as on a solid foundation. Whenever, therefore, dangers press upon us from every side, let us learn to turn to this place of refuge. The words of the Psalmist agree with this sentiment:

The heavens shall wax old and vanish away; but You, Lord, are always the same, and Your years are not changed (Psalms 102:26, 27).

Both passages remind us that the grace of God, which He displays in the preservation of His Church, surpasses all His other works. Everything contained in heaven and earth is frail and fading; but God’s salvation, by which He guards the Church, is eternal and therefore cannot be liable to these dangers.