Perceiving angels
Genesis 18
While Abraham was sitting at the entrance to his tent in the heat of the day, near the great trees of Mamre, he looked up and saw three men standing nearby. When he saw them, he hurried from the entrance of his tent to meet them and bowed low to the ground. He said, "If I have found favour in your eyes, my lord, do not pass your servant by. Let a little water be brought, and then you may all wash your feet and rest under this tree. Let me get you something to eat, so that you can be refreshed and then go on your way - now that you have come to your servant." "Very well," they answered, "do as you say."
Middle Eastern hospitality, offered to passing strangers. When Abraham says "my lord", "your servant", he hasn't guessed their identity - it's just the polite way to address strangers that one is offering hospitality to. They just appear to be three men - no wonder Sarah laughs when they tell her that she will bear a child within the year - what can they know, she thinks.
But Abraham, who had met God before, had guessed the identity of at least one of them. Sometimes it has been thought that these three men are the three persons of the Trinity; but the text doesn't bear that out - verse 22 states that the men went away to Sodom, while the LORD stayed behind and bargained with Abraham for the fate of the city; and when the men arrive at Sodom they are described as two angels. Neither Lot nor the people of Sodom realise at any point that the visitors are angels - the angels have great difficulty convincing Lot and his family that they are in danger, and end up having to grab them by the hands and drag them out of the doomed city by force.
In Judges 13 another childless couple have a mysterious visitor. In the words of the woman, "A man of God came to me. He looked like an angel of God, very awesome. I didn't ask him where he came from, and he didn't tell me his name. But he said to me, 'You will conceive and give birth to a son.'" Manoah, her husband, prays for the man to return, and he does so; Manoah treats him with the hospitality and reverence due to a prophet or holy man, but, the Bible comments, Manoah did not realise that it was the angel of the LORD. He asked the stranger his name, but the man replied, "Why do you ask my name? It is beyond understanding." The stranger politely refuses to eat their food, but suggests they offer it to the LORD. It is only when they set fire to the offering and the angel flies up to heaven in the flames that they realise that their visitor was not, perhaps, human! The child, incidentally, was Samson.
In several places in the Old Testament it is not clear whether 'the angel of the LORD' is an angel or the LORD himself. In Genesis 16:7 onwards, Hagar, Sarah's maidservant, is running away from her mistress, who has ill-treated her; and she is met by 'the angel of the LORD', who comforts and looks after her. Although the mysterious person is called throughout 'the angel of the LORD' and not simply 'the LORD', Hagar reacts as if she had actually seen and spoken to God. In Judges 6, the stranger who visits Gideon is sometimes referred to as 'the angel of the LORD' and sometimes as simply 'the LORD'; neither the writer of this passage, nor Gideon, seem to be able to make up their minds. A traditional Christian interpretation of this ambiguity is that this particular angel was a manifestation of Christ before the Incarnation, as God's Messenger Servant. It may be, however, that as the LORD's personal representative the angel could speak as if he were God. The angel is, so to speak, transparent; you look at the angel, but all you can see is God shining through him. The angel speaks, but you hear God's voice.
The inability of Lot and the people of Sodom to perceive the angelic nature of their visitors suggests that the ability to see through an angel's disguise is related to spiritual sensitivity. It almost seems like a rule in the Bible, that the closer a person is to God, the more immediately they recognise His messengers. Manoah and especially his wife immediately sense something special about their visitor; Gideon is a bit suspicious and takes about five minutes; and if you want a contrast to Lot, consider the Virgin Mary, who spotted that her visitor was an angel straight away!
On the other hand - on the morning of the Resurrection, Mary Magdalene, standing outside Jesus' empty tomb, doesn't appear to notice that the two men sitting in the tomb dressed in white are angels; she is, I suppose, too busy crying over her loss to take much notice of them, except perhaps to turn away embarrassed that someone has caught her crying. Her mind is on other things.
Which inevitably leads to the question: How often have we failed to perceive angels? The Bible narratives suggest that they don't always look extraordinary, especially when meeting people in public places.