Sometimes it is said in spiritual endeavor that the student must have complete faith -- in the teacher or teachings or whatever. Have...no...doubt!
OK. As far as it goes, it sounds pretty good. Hard, perhaps, but ... well, OK.
The fly in the ointment is that often (always?) the matter of faith is equated with belief ... to have an unalloyed faith is to believe in the teacher or teachings.
Anyone who examines belief knows that without doubt, belief hasn't got a leg to stand on... it's like talking about water and wetness.
And from this, I figure it is fair to deduce that complete faith points to something other than any belief, however well-adorned it may be.
It's not a criticism. Just an observation.