John Calvin Commentary Genesis 7:17

"And the flood was forty days upon the earth; and the waters increased, and bare up the ark, and it was lifted up above the earth." — Genesis 7:17 (ASV)

And the flood was forty days, etc. Moses strongly emphasizes this fact to show that the whole world was immersed in the waters. Moreover, it is to be regarded as the special design of this account that we should not attribute to chance the flood by which the world perished, however customary it may be for people to conceal the works of God, which may obscure either His goodness or His judgments revealed in them.

But since it is plainly declared that whatever was flourishing on the earth was destroyed, we therefore infer that it was an indisputable and remarkable judgment of God, especially since Noah alone remained secure because he had embraced by faith the word in which salvation was contained. He then reminds us of what we have said before: namely, how desperate the impiety and how enormous the crimes of humanity had been, which prompted God to destroy the whole world; whereas, because of His great mercy, He would have spared His own creation if He had seen that any milder remedy could have been effectively applied.

He connects these two things, directly opposed to each other: that the whole human race was destroyed, but that Noah and his family safely escaped. From this we learn how beneficial it was for Noah to disregard the world and obey God alone. Moses states this not so much to praise the man as to invite us to imitate his example.

Moreover, lest the multitude of sinners draw us away from God, we must patiently endure being ridiculed and triumphed over by the ungodly, until the Lord shows by the final outcome that our obedience has been approved by Him. In this sense, Peter teaches that Noah’s deliverance from the universal deluge was a figure of baptism (1 Peter 3:21), as if he were saying, the method of salvation, which we receive through baptism, corresponds with this deliverance of Noah.

Since, in our time also, the world is full of unbelievers as it was then, it is therefore necessary for us to separate ourselves from the greater multitude, so that the Lord may snatch us from destruction.

In the same manner, the Church is fittingly and justly compared to the ark.

But we must keep in mind the likeness in which they correspond, for that likeness is derived from the word of God alone; because just as Noah, believing the promise of God, gathered himself, his wife, and his children together, so that under a certain appearance of death, he might emerge from death, so it is fitting that we should renounce the world and die, so that the Lord may give us life by His word. For nowhere else is there any security of salvation.

The Papists, however, act ridiculously in fabricating for us an ark without the word.