Christ warned us that in the last days before his return that our societies, our lifestyles, our economies, our world would be just as it was during the Days of Noah:

'But as the days of Noah were, so shall also the coming of the Son of man be. ' Matthew 24:37

Now what occurred during the days of Noah to make God decided that he wanted to destroy the entire world? Some would say sin, but "Sin" is breaking Gods Laws and/or doing anything that is forbidden of the Lords Commands. Did God Command the world during the days of Noah to follow his instructions, his laws, his ways? Did they start to stray from the ways of God, like we are today and is this the real reason why God destroyed the world during the days of Noah:

"And when Enoch had ascended into heaven, all the kings of the earth rose and took Methuselah his son and anointed him, and they caused him to reign over them in the place of his father. And Methuselah acted uprightly in the sight of God, as his father Enoch had taught him, and he likewise during the whole of his life taught the sons of men wisdom, knowledge and the fear of God, and he did not turn from the good way either to the right or to the left. But in the latter days of Methuselah, the sons of men turned from the Lord, they corrupted the earth, they robbed and plundered each other, and they rebelled against God and they transgressed, and they corrupted their ways, and would not hearken to the voice of Methuselah, but rebelled against him." Jasher 4:2-4

Noah preached to the world for 120 years. Proclaiming to them to follow the Laws, Ways, Commandments of the Lord, but they refused to listen:

“And after the lapse of many years, in the four hundred and eightieth year of the life of Noah, when all those men, who followed the Lord had died away from amongst the sons of men, and only Methuselah was then left, God said unto Noah and Methuselah, saying, Speak ye, and proclaim to the sons of men, saying, Thus saith the Lord, return from your evil ways and forsake your works, and the Lord will repent of the evil that he declared to do to you, so that it shall not come to pass.For thus saith the Lord, Behold I give you a period of one hundred and twenty years; if you will turn to me and forsake your evil ways, then will I also turn away from the evil which I told you, and it shall not exist, saith the Lord. And Noah and Methuselah spoke all the words of the Lord to the sons of men, day after day, constantly speaking to them. But the sons of men would not hearken to them, nor incline their ears to their words, and they were stiffnecked. And the Lord granted them a period of one hundred and twenty years, saying, If they will return, then will God repent of the evil, so as not to destroy the earth.” Jasher 5:6-11

In order for us to heed the words of Christ and be on alert for the signs of this world going as the Days of Noah did. We must know what occurred, why did God destroy the world? I know it sounds like a broken record, but God is not a man that he should lie and he does not change. God destroyed the world during the Days of Noah because they refused to follow his commands and therefore they sinned!