Long ago, St. Augustine of Hippo wrote a book commonly called “The City of God”. In it he chronicled that:
“we have learned that there is a city of God, and its Founder has inspired us with a love which makes us covet its citizenship. To this Founder of the holy city the citizens of the earthly city prefer their own gods, not knowing that He is the God of gods” – St. Augustine “City of God” Bk. XI. Ch. 1
In short, sinful man sees God’s city (spoiler alert) which is the Church of Christ, and decides that it’s more pleasurable to continue in the City of Man, without the true God. However, Christ has sent ‘word’ to man (the Scriptures) which the City of God proclaims, and those who are called to faith in this preaching then become inspired with love and join God’s City.
So these two cities continue to this day. The City of God turns out to be the Church of Christ, and the City of Man turns out to be the Kingdom of Satan. Men have heard the call of each at times, Man has been brazen enough to call his own city, the City of God (whether it be the Renaissance Papacy’s claim of total spiritual and temporal power, or the American Dissenter’s claim to be a “City on a Hill”).
Throughout the history of God’s City, there have been times of extremely low populations. One such instance was the flood Noah endured in Genesis 6. Noah had been a righteous man who walked with God, and had presumably heard God’s promise already given (Gen. 3:15) that one day a woman would conceive of a Saviour who would be Lord even over man’s greatest enemy. Noah was also given Word from God to preserve the City of God by building an ark.
Writing on the subject, Martin Luther noted:
“Nor must we trust in holiness of origin, in forefathers, or in the gifts of God which we enjoy. We must look to the Word alone and judge thereby. Those alone who truly embrace the Word will be as immovable forever as Mount Zion. They may be few in number and thoroughly despised by the world, as were Noah and his children. But God, through these few, preserved to man the truth of that promised mastery when he had not even room to set his foot upon the earth”
and elsewhere in the same commentary:
“Let us say with Noah: I know that I am righteous before God, even though the whole world condemn me as heretical and wicked, yea, even desert me. Thus did the apostles desert Christ, leaving him alone; but he said (Jn 16, 32): “I am not alone.” Thus did the false brethren desert Paul. Hence, this is no uncommon danger, and it is not for us to despair; but with courage to uphold the true doctrine, in spite of the world’s condemnation and curse.”
The test of faith for those in the City of God was always to stand for God’s word despite what the City of Man threw at them. The temptation for the Church has thus always been, to try to make the City of Man, the City of God and in conflating them it has only ever succeeded in corrupting the City of God.