With the quote above by Dr. John F. MacArthur saying that Christians are a preservative in the midst of a decaying civilization, I really think of the Abraham negotiating with God concerning the destruction of Sodom (Genesis 18:16-33). The world is getting more and more wicked by the second or even by the split second because of how fast sins can get legalized. What is legal to man is not necessarily legal in the Law of God. Satan is moving faster than ever because he knows his time is short and he wants to take as many people to Hell to suffer with him for all eternity.
I always hear talks of people who say that if Christians were out of the way, the world would meet unlimited human progress. I hear sin-loving people who wish that the Christians would be fully eliminated from the face of the Earth because they are a prick to their sins. What they do not realize is that the faithful remnant and that having more than fifty righteous people in the midst of a wicked nation is the only reason why God has not yet fully judged a nation. Whenever I complain about the sinfulness of society, I realize that God has not fully judged a nation yet for the sake of more than fifty righteous people namely the truly saved, true converts in Christianity.
The parable of the wheat and the tares shows this fact. Matthew 13:24-20 shows the illustration of the wheat and the tares. While there was a plantation of wheat, the enemy sowed tares. The wheat represent the saved and the tares represent the unsaved. What we read is that God has delayed judgement for a good reason because the good wheat would be removed. Instead, God waits for both the wheat and the tares to ripen before the great harvest in Revelation 14:14-20 can even take place. In one sense, everyone begins as a tare and Satan plants the unsaved everywhere. He can plant unbelievers here and there and remember, tares cannot become wheat unless a spiritual rebirth takes place. God still sees some tares who will repent and they become wheat then when the hour glass is up, it's time for harvest.