It is written:
“We told you the true Good News message. So anyone who tells you a different message should be condemned—even if it’s one of us or even an angel from heaven!” (Galatians 1:8)
Muhammad’s experience with “Gabriel” actually is pretty frightening to consider. We are told that the angel appeared to him and began to choke him unconscious, telling him that he needed to “submit.” In fear, he ran to his wife. What we are told next is very informative. Norman Geisler has written:
“”One of the most widely respected modern Muslim biographer, Muhammad Husayn Haykal, speaks vividly of Muhammad’s plaguing fear that he was demon possessed: Stricken with panic, Muhammad arose and asked himself, ‘What did I see? Did possession of the devil which I feared all along come to pass?’ Muhammad looked to his right and his left but saw nothing. For a while he stood there trembling with fear and stricken with awe. He feared the cave might be haunted and that he might run away still unable to explain what he saw. [74, emphasis added]. “Haykal notes that Muhammad had feared demon possession before, but his wife Khadijah talked him out of it. For “as she did on earlier occasions when Muhammad feared possession by the devil, so now stood firm by her husband and devoid of the slightest doubt.” Thus “respectfully, indeed reverently, she said to him, ‘Joy to my cousin! Be firm. By him who dominates Khadijah’s soul I pray and hope that you will be the Prophet of this nation. By God, he will not let you down’” (ibid., 75). Indeed, Haykal’s description of Muhammad’s experience of receiving a “revelation” fits that of other mediums.” (Norman Geisler, Baker Encyclopedia Of Christian Apologetics, 505 (Kindle Edition); Grand Rapids, Michigan; Baker Books).
As we will learn, Muhammad was a well-known and practiced medium, which makes it very likely that his experiences were not with the angel Gabriel at all.