Why didn’t God start mankind completely over at the Flood?

There is one very good reason why God did not just kill all of mankind completely and create a new set of people in the world:  sin.  Even though sin was the reason for the judgment of the Flood, it was also the reason why God did not just wipe all mankind out as well.  There were people who chose to follow and serve God, who loved Him, and put their faith in Him (Abel, Enoch, Noah; Hebrews 11:4-7).  If God would have started all the way over and wiped out all of Adam’s descendants, then He would have lied to Adam when He promised a Savior for mankind right after the fall of man (Genesis 3:15).  On top of this, God had it planned out from before time began what He was going to do and how salvation was going to be brought into the world to have people who truly want to love God and be with Him for eternity (Ephesians 1:4-12).  God knew Adam would sin but provided a way out for him and his descendants.  If God just wiped everyone out and started over He would go against Himself, and this is something that God cannot do.