To expand on the symbolism of the words I will destroy them together with the earth (I have decided to destroy all living creatures –Genesis 6:13 NLT) as the fact that the human race would meet its end along with the church: If the Lord’s church were completely obliterated from the planet, the human race could never survive. Every last person would die.
The church resembles the heart. As long as the heart thrives, so can the surrounding organs and limbs. But as soon as the heart dies, everything else dies too. The Lord’s church on earth is like the heart; from it the human race—including people outside the church—receives life. Since no one has the faintest idea why this is so, I wish to explain.
The situation of the earth’s entire population resembles that of the human body with all its parts. In this body, the church plays the role of the heart. If there were no church supplying the heart’s place—a church with which the Lord could be united by means of heaven and the world of spirits—a break would occur. And if there were a break between the human race and the Lord, we would be annihilated immediately.
For this reason, a church has always existed, ever since the first moment of humanity’s creation. Even when the church has begun to die out, it has always remained alive in a few people.
The Lord came into the world for the same reason. Had divine mercy not prompted him to come, the whole human race on this planet would have been destroyed, because at that time the church had reached its last stages and hardly any goodness or truth was left.
Because we humans, regarded in ourselves, are much lower than animals, we have no chance at survival unless we are intimately connected with the Lord through heaven and the world of spirits. Left on our own we would plunge headlong into destroying ourselves and everyone else, because the ruination of ourselves and everyone else is all we long for.
Our proper code of life is to love one another as we love ourselves, but what we actually do these days is to love ourselves more than others and thus hate everyone else. Now, with unreasoning animals the case is totally different. Their proper code is the one they live by, and so they live in thorough harmony with their destiny. We humans, though, live exactly opposite to the pattern ordained for us, so if the Lord did not take pity on us, if he did not bind us to him through angels, we could not possibly survive a single moment.
Of this fact humanity is unaware.
from Secrets of Heaven, Volume 1, Section 637