I dislike the use of the term term Angel here. Aliens are physical beings, Angels are supernatural/spiritual beings.
Alien just means foreign.
You can easily tell the difference between Aliens and Angels in the bible. Angels appear supernaturally like Gabriel did to Mary,
hmm -- lets try Genesis 18 and 19
Gen 18
Then
the Lord appeared to him by the terebinth trees of Mamre, as he was sitting in the tent door in the heat of the day. 2 So he
lifted his eyes and looked, and behold, three men were standing by him; and when he saw them, he ran from the tent door to meet them, and bowed himself to the ground, 3 and said, “My Lord, if I have now found favor in Your sight, do not pass on by Your servant. 4
Please let a little water be brought, and wash your feet, and rest yourselves under the tree. 5 And I will bring a morsel of bread, that you may refresh your hearts. After that you may pass by, inasmuch as you have come to your servant.”
...
Abraham Intercedes for Sodom
16
Then the men rose from there and looked toward Sodom, and Abraham went with them to send them on the way. 17 And the Lord said, “Shall I hide from Abraham what I am doing, 18 since Abraham shall surely become a great and mighty nation, and all the nations of the earth shall be blessed in him? 19 For I have known him, in order that he may command his children and his household after him, that they keep the way of the Lord, to do righteousness and justice, that the Lord may bring to Abraham what He has spoken to him.” 20 And the Lord said, “Because the outcry against Sodom and Gomorrah is great, and because their sin is very grave, 21 I will go down now and see whether they have done altogether according to the outcry against it that has come to Me; and if not, I will know.”
22
Then the men turned away from there and went toward Sodom, but Abraham still stood before the Lord. 23 And Abraham came near and said, “Would You also destroy the righteous with the wicked? 24 Suppose there were fifty righteous within the city; would You also destroy the place and not spare
it for the fifty righteous that were in it? 25 Far be it from You to do such a thing as this, to slay the righteous with the wicked, so that the righteous should be as the wicked; far be it from You! Shall not the Judge of all the earth do right?”
Gen 19
Now the two angels came to Sodom in the evening, and Lot was sitting in the gate of Sodom. When Lot saw
them, he rose to meet them, and he bowed himself with his face toward the ground. 2 And he said, “Here now, my lords, please turn in to your servant’s house and spend the night, and wash your feet; then you may rise early and go on your way.”
And they said, “No, but we will spend the night in the open square.”
3 But he insisted strongly; so they turned in to him and entered his house.
Then he made them a feast, and baked unleavened bread, and they ate.
4 Now before they lay down, the men of the city, the men of Sodom, both old and young, all the people from every quarter, surrounded the house. 5 And they called to Lot and said to him,
“Where are the men who came to you tonight? Bring them out to us that we may know them
carnally.”
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Angels can appear in physical form as humans or as whatever form they wish. And in this example the humans could not tell the difference.