The following chapter provides an important clue. Genesis 19 identifies two of the visitors who arrived in Sodom as angels. This has led many Christian commentators to understand the third visitor as a special manifestation of the Lord.
Some Christian interpreters believe this may have been an appearance of the eternal Son of God before His incarnation, sometimes called a Christophany. Others understand the encounter as God making His presence known through an angelic representative who spoke with divine authority.
Christian tradition has also found Trinitarian symbolism in the three visitors. One famous example is the traditional icon of the Trinity depicting Abraham's guests. However, Genesis does not explicitly identify the three men as the Father, Son, and Holy Spirit, and that symbolism should not be confused with a direct statement of the text.
The account emphasizes that Abraham was receiving a divine message and that the seemingly impossible promise of Isaac's birth would be fulfilled.