According to the Scriptures
Christ died for our sins according to the Scriptures, and that He was buried, and that He was raised on the third day according to the Scriptures
(1 Corinthians 15:3-4)
When Paul wrote these words to the Corinthians, he understood the historical background of the passion of Christ as the culmination (fulfilment) of the event that delivered a nation from the slavery and oppression of Egypt to freedom and redemption. I like the way he introduced this to the Romans, “The gospel of God, which He promised beforehand through His prophets in the Holy Scriptures, concerning His Son, who was born of a descendant of David according to the flesh, who was declared the Son of God with power by the resurrection from the dead, according to the Spirit of holiness.” These scriptures were the same that Paul encouraged Timothy to continue in the things which he “learned and become convinced of” (1 Timothy 3:14). He reminded him that “from childhood you have known the sacred writings which are able to give you the wisdom that leads to salvation through faith which is in Christ Jesus. (1 Timothy 3:15).
The reason for the Gospel is because “the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men who suppress the truth in unrighteousness (Romans 1:18). Man was condemned because Adam introduced corruption into the world by his transgression (Romans 5:12). Here is a brief summary of what happened according to Genesis 1-11:

Chaos to order in creation
Disunity between God and man with the transgression of Adam
Judgment of the world by the flood
Human attempt at unity with the Tower of Babel