Some say this episode was an actual occurrence in the external world. Since
@Thomas will not answer the question clearly, I will try to answer it for him. If
@Thomas were present during this episode, then he would have seen three strangers that eat, drink, get their feet washed, and talk with Abraham and Sarah. They are obviously men (although some might conclude they are angels or the Lord in the form of men). Assuming this reading is the correct one,
@Thomas would have heard and seen Sarah laughing and kneading cakes too.
Some say Abraham had a vision or a dream. So, if
@Thomas were present near Abraham during this episode, he would have seen a man having a vision. Nothing else and nothing more. He would have not been aware of any "angels" nearby, because he would have concluded Abraham is having a discourse with "incorporeal beings" in a vision, I suppose. Also, he would not have heard and seen Sarah laughing or kneading cakes.
In both scenarios a witness of the event can conclude there were no angels present if they are unaware that they are angels, so I still have no clue which side
@Thomas is taking here. The same issue arises with "angels came and attended him [Jesus]" (Matt. 4.11). A vision of "incorporeal beings" or not? Priests/holy ones/angels attended him? Same issue with other passages like Exodus 23.20-21: "See, I am sending an angel ahead of you to guard you along the way and to bring you to the place I have prepared. Pay attention to him and listen to what he says. Do not rebel against him; he will not forgive your rebellion, since my Name is in him." Is the angel the high priest (who also carries "the Name" on his attire) or what I guess Christians would take to be an "incorporeal being" in a vision?
I was hoping
@Thomas was going to vividly paint the picture for me, but, instead, I got Hebrews 13.12, but I think he means Hebrews 13.2. I suppose he is siding with St. Augustine since he concluded that they are angels: “Actually, these men were angels, as is clear from the witness of Scripture not only here in the Book of Genesis where the episode is recorded but also in the Epistle to the Hebrews, where, in a sentence praising hospitality, it is said: 'Thereby some have entertained angels unawares.'" The Orthodox Church, however, takes a view similar to Justin Martyr: "One of those three is God, and is called Angel, because, as I already said, He brings messages to those to whom God the Maker of all things wishes, then in regard to Him who appeared to Abraham on earth in human form in like manner as the two angels who came with Him, and who was God even before the creation of the world, it were reasonable for you to entertain the same belief as is entertained by the whole of your nation." St. Augustine rejects this interpretation.
Anyway, the issue is the same: How can an incorporeal being have "discourse" with humanity except through matter? Abstract substances can only have effects through matter. The three strangers are all human beings.