Noah lived in a time of uncertainty when evil was everywhere and he built the Ark (Genesis 6). Abraham coexisted with uncertainty when he up and left his homeland (Genesis 12). Shadrach, Meshach, and Abednego were surrounded by uncertainty when they refused to worship the idol of Nebuchadnezzar's (Daniel 3). They all lived in a time of uncertainty and it isn't any different today. God has looked down on the nature of man and said that he would not always strive with man (Genesis 6:3). There is a day coming. That is certain. The uncertainty is not knowing when.
Jesus was sitting on the mount of Olives with his disciples and they were curious about the end of the world. Here we are over two thousand years later and we still wonder the same thing. He goes on in Matthew 24 and tells them that the end is not yet and what the things are that must come to pass before God brings down the curtain on this old world. From what he describes it will be just as wicked as many of the events described in the Bible. The warnings of what to expect begin in Matthew 24:16-21. Those in Judea, flee into the mountains, don't stop to get anything, just go. It will be awful for expecting and nursing women. Pray that it won't be in winter or the Sabbath. Finally, it'll be the worst tribulation since the beginning of the world.
Since the beginning of the world. Let that sink in. Sodom and Gomorrah were decimated along with the plains around it. God rained down brimstone and fire from out of heaven and destroyed all the inhabitants for their wickedness (Genesis 19:24). Lesson number one: The sins of Sodom and Gomorrah were great enough to cause God to rain down fire and brimstone until they were destroyed. This was only two towns. At a future time known only to God, the sins of this earth will be so great that the "heavens will pass away with a loud noise, and the elements shall melt with fervent heat, the earth also..." (II Peter 3:10).
Nineveh was another matter. That great Assyrian city came up before God for its' wickedness. Jonah, after some convincing, was sent there to preach that Nineveh was going to be overthrown unless they repented. They did repent, and so they were secure for a time. Historical accounts report that about 200 years later, the city was destroyed and the inhabitants carried away. Lesson number two: Repent and be saved. God sent his prophet to warn them and they paid attention. II Peter 3:9 says the Lord is...not willing that any should perish, but that all should come to repentance. Unfortunately their repentance became slack and the city became only a footnote in history.
Times are uncertain and no one knows what the future holds or if there's a future. What's important is found in Revelation 3:3. "Remember therefore how thou has received and heard, and hold fast, and repent. If therefore thou shalt not watch, I will come on thee as a thief, and thou shalt not know what hour I will come upon thee."