…the possibility that humans become angels when they die.
I have never understood how anyone who has read the New Testament as a whole would be led to believe that a human being becomes an angel after death. In the context of the teaching of Jesus, the Acts of the apostles, the epistles, and Revelation, it is clear that the redeemed members of humankind will be physically resurrected in the full glory of humanity (like Jesus) to live on a redeemed earth and the heavens.
However, because of the de-emphasis of physical resurrection in the theology of the last 50-75 years, and the mistaken belief that the present earth will be destroyed, the angel narrative in the popular culture has intruded into popular theology.
So passages like Matthew 22:30 (“For in the resurrection they neither marry or are given in marriage, but are like angels in heaven”) are ripped from their context and are cited to claim that human beings become angels, somehow before human beings are resurrected.
No. Read 1 Corinthians 15:12-58 carefully (don’t worry about understanding all of it immediately) and you will see that everything Paul teaches is focused on the resurrection of our physical bodies. Since I am not currently an angel, and I suspect you are not either, we will be resurrected as human beings at the end of the age.
When the believers thought that Peter had died, they said it must have been his angel waiting at the door…
Regarding this passage in Acts, as I understand it, there is a very ancient tradition that the believers in Acts are referencing. The tradition is that, in some circumstances, angels appear to people in the form of a friend to aid or assist, so as not to terrify the person who is troubled. (Note that every time an angel appears to someone not in disguised form, mere mortals are terrified.)
I first learned of this back in college when there were some of us believers who started praying for and witnessing to teens and young adults in a local self-styled satanist cult. We faced a LOT of spiritual blow-back and attacks for it and I learned firsthand the power of Jesus over evil. One evening. one of my college professors was led to go confront the entire group during a ritual we knew about, and I offered to go with him. He asked me not to go with him but to keep him in prayer. So I prayed as I drove in the opposite end of town to keep a date with a young woman. On the way, my labored prayer gave way to ease and joy, and I knew it had been answered.
The next morning, I was confronted on my way to breakfast by a young woman who was tangentially part of the satanic group. She was furious with me because she claimed the professor and I had gone to the meeting and somehow “scared” everyone where they were vomiting and fainting. I told her that I wasn’t there, I was on a date, but she didn’t believe me, since she and everyone else could clearly see me with the professor.
I went immediately over to the professor’s office (I knew he prayed for all his students from 6:30-7:30am), and knocked on his door.he seemed to be expecting me. I asked him what happened and he said he was nervous about going out there, but the Lord have him courage on the way. He said he stepped out of his car and people came pouring out of the house where they were meeting and running into the woods behind the house to hide. He said “the Lord gave them a show” and he preached to them about renouncing the works of darkness and coming into the light of Jesus. Then, he left.
i asked, who was with you? He said, “God was with me, but I left by myself.” I told him how it had been reported to me that I had been with him, and he said, “Oh!,” smiling, “I suppose I shouldn’t be surprised that they saw someone.” I pressed him on that point, wanting to know what he meant by that and what he saw. He refused to talk about it.
It was later, when I told a patristics scholar friend about it that he mentioned the tradition of angels in the disguise of friend. I suspect that the professor thought that I might become obsessed with signs, miracles, angels, etc., or consider him a greater man than he was (he was/is a great man), so he decided to model humility and keep the secret.