First of all the man WAS a muslim. I say WAS because he immediately became a committed follower of Jesus after the encounter he had with the angel. He's been threatened by more radical muslims who he has told about this experience. He is sticking to his story, his experience and most radically, he's sticking to being a follower of Jesus! This alone would convince me of the validity of the experience. He is suffering already for this encounter and is willing to joyfully.
So what exactly was the experience? About 1 year ago, while he was awake in the night a brilliant creature entered his bedroom in the middle of the night. He's told many people about the experience (mostly muslims who think he is crazy). Every time somebody tried to relate to the angel's brilliance of light, he would say it was like "no light that is found on earth". I told him that God dwells in "unapproachable light" and that the angel came down clothed in the light that surrounds God to shelter His even more brilliant glory. He said, "finally someone who understands what I saw and experienced"! Actually, I don't understand (experientially) but I know what the God's Word teaches.
I find it extremely interesting that the ONLY people who believed him were Egyptian Coptic Orthodox Christians (the only Christians he knew). Muslims don't believe that angels can or do visit people any more (that ended in their view with their prophet who was the last person according to their theology to ever receive direct revelation from heaven/God).
The second reason I believe him is the nature of the encounter FITS what I know of angelic visitations (both in Scripture and throughout Church History). Angels come with "a message". This one came to declare something that no muslim would EVER expect God to say to them or about them (at least before Judgement Day). This angel came to tell him, in his own language (Farsi) that he was "pure and acceptable to God". Why would that be significant? Because he had been questioning islam for a few years (he was no longer 'buying it' - the violence, the fear-based admonitions, the character/nature of God in their concept, and the lack of freedom muslims had to follow another path if they so desired. In other words, it really bothered him that islam killed people (or are supposed to) who leave that religion. In case you don't believe me, Google "the law of apostasy in islam".
Angels in the Scriptures would come to do exactly what this one did for my new friend - to assure him of God's favor and leading in his life, to confirm the Word that he was beginning to believe and to confirm that the Christian message was in fact the truth of God for muslims and all mankind. As he sat there telling me that Jesus is truly the Son of God (something muslims vehemently disbelieve), I knew that this couldn't have been anything other than what he claimed it to be.
this man had been listening to Christian satellite television being broadcast in his own language and essentially the angel appeared to "confirm" what he had begun to believe. Could it really be that by following Jesus, his sins would be declared forgiven and he would be deemed acceptable in God's sight? that is not something islam offers its followers. in short, there is no assurance of salvation in islam. to declare that one "knows" they have been accepted by God and are assured of heaven is blasphemy in islam.
The third reason I believe him is that he couldn't talk about anything else. For him, his life essentially began on that night 10 months ago. Just so he knew he wasn't crazy, the angel actually appeared to him a second time. not with a message, but just to let him know that the experience was genuine. As we sat in a public place, with many muslims walking by us (and some seemingly listening in to his recounting the story), I knew that this man was unafraid to talk about this encounter with anyone and everyone who would listen.
Actually, I told him while we talked that his experience is actually one of the primary ways that muslims leave islam and become followers of Jesus - either angelic visitations like his, or Jesus Himself appearing to them and inviting them to follow Him.
Truly this man was "touched by an angel"!