The Salvation Plan in Genesis

I have been thinking heavily about the destruction of Soddom and the conversation that abraham had with God beforehand. That conversation has been showing me that God values righteousness, that God is just, and that God is merciful. That God, though He did not have to, would have spared all of the sinful people of that city but for the sake of only a few. And then it hit me how this story foreshadows the salvation plan. That God would spare the unrighteous and undeserving (that's us) because of one man (Jesus, obviously). This realization was awesome to me and reaffirmed that God's plan for salvation was from the beginning, not just an afterthought.