Do angels walk among us?
I do not think it is possible to give a definite answer to this question. Hebrews 13:2 gives us the admonition, “Do not neglect to show hospitality to strangers, for thereby some have entertained angels unawares.” This certainly indicates that at the time of the writing of Hebrews there was a danger of ignoring proper hospitality to strangers, recognizing that there might be angels among them.
In the Old Testament, there were certainly many appearances of angels. Two angels accompanied the Lord as they were entertained by Abraham (Gen. 18:2; 19:2,3). In the gospels, angels are mentioned several times (e.g., Jn. 5:4; Lk. 22:43). In particular, they announced the coming of the Savior (Matt. 1:20; Lk. 1:11–38). In the New Testament outside the gospels, early Church period in Acts (Acts 5:19, 10:3-7, 12:8-11, 27:23), and the book of Revelation, there are a number of references to angels, but only the reference in Hebrews explicitly mentions angels visiting hospitable believers. For example, angels are referenced metaphorically in 1 Corinthians 13:1, as heavenly authorities in 1 Corinthians 4:9, and so on.
Why would not the reference in Hebrews be sufficient to prove that “angels walk among us”? I do take the admonition in Hebrews seriously. We need to be gracious to “strangers”, which I think is the main point. Someone we do not know may indeed be an angel. However, I do not think we can take the verse in Hebrews as a proof text that they do walk among us today.
We need to remember that the book of Hebrews has a very Jewish flavor. One of the major purposes of the book is to outline the distinction between the old Jewish (Old Testament) perspective with the perspective presented in the New Testament (Col. 1:18, Heb. 1:1-2). Angels are mentioned more times in Hebrews (12) than any other New Testament book. This reflects the fact that angels were more prominent in the Old Testament age than in the present Church age.
It may be that angels today are given special assignments for our protection (Ps. 91:11, Matt. 18:10, Heb. 1:14). So, I will end with a story, which I cannot validate because the participants are now with the Lord and I received the story second-hand. A prominent preacher of the gospel who I personally knew to be a man of very high integrity was traveling and accidentally left his briefcase containing his Bible somewhere in the airport (perhaps the washroom…I do not know). Realizing his loss sometime later he hurried back down the halls and found a stranger standing “guard” over his briefcase. Picking up the briefcase he looked around and the stranger was nowhere to be seen. Was this an angel? I cannot say, but it is not unlike what I might expect of their care over us as directed by our Lord.