Just like Melchizedek in Genesis 14, we meet some characters that cause us to ask, “Who are you?” Of the three men we see, one, at least, seems to be a manifestation of God’s presence with Abraham (in 18:3, “lord” is the word used for God). It is not uncommon to encounter characters in the Old Testament whose identities are shadowy to us. Again, my goal isn’t to situate every character’s identity perfectly. To be honest, the presence of the three men leads to much head-scratching and speculation; that can be fun, but it can also cause us to miss the greater point. What is important here is to understand that God reiterates to both Abraham and Sarah the promise of a son. Sarah, like Abraham before her, laughs at this pledge. It seems that she had ceased having menstrual cycles (Genesis 18:11), making her biologically incapable of child-bearing. In case the reader doesn’t understand, God is going to do something for Abraham and Sarah that they are completely unable to do. This is simply what God does for His people throughout scripture. We are incapable of giving ourselves life, of providing food, of running a universe suited for thriving–and of paying the penalty of sin or coming back to life. Here, God shows He is the sort of God that delights to do for us what we cannot, according to His good purposes. As we will see, that is what the Gospel, the good news of this whole book, is all about.