The practitioners of the Muslim cult are the ones who should be in mental institutions...
Exactly.
Compare the facial expressions in this photo. Rahman's face has a soft and smiling quality even though he is the one facing possible death. The others have an aspect of anger or sadness.
It is not at all surprising that a Spirit-filled Christian would appear insane to devout muslims.
BTW, look at the expression of Rahman's hands (over his heart). We can pretty clearly surmise what he is saying.