Blessings to all,
Welcome again, I am Jerry, this portion of our study covers:

GOD REAFFIRMS HIS PROMISE part 1

Until you get to the New Testament, you may wonder why the eighteenth and nineteenth chapters of Genesis are included in the Bible. They seem rather detached from the story of Abraham. They deal with the destruction of Sodom and Gomorrah. Chapter 18 is a rather lengthy chapter in which God tells Abraham about the judgment of Sodom and Gomorrah and Abraham intercedes on behalf of the cities of the plain.

This is an illustration, I think, of the blessed Christian life, of life in fellowship with God. But in chapter 19, down in Sodom and Gomorrah with Lot, we will see what I would call the blasted life—all because of a decision that was made. Unfortunately, we have both kinds among Christians today—those living a blessed life and those living a blasted life. 

There are those who have really made a shipwreck of their lives; they have gotten entirely out of the will of God. I would not suggest even for a moment that they have lost their salvation, but they sure have lost everything else. As Paul says, they are saved, “. . . yet so as by fire” (l Cor. 3:15).
The events of Genesis 18 take place not long after God's visit with Abraham in chapter 17. 

This visit from the Lord is quite different, however. It's not clear, at first, if Abraham even recognizes the three men who appear outside of his tent as the Lord and two angels in human form. In either case, Abraham runs to show them deep respect and hospitality. He tells Sarah to bake them bread and has a young calf slaughtered for them to eat as they rest in the heat of the day.