What is the guidance and counseling regarding the confusion between shortening the beard out of detestation and inquiring about the nature of this detestation, while feeling a loss of faith and doubt in everything?

The distinction the questioner makes between natural dislike and legislative dislike, and the subsequent belief in the disbelief of the self and the abandonment of prayer, is invalid. The questioner's statement, "I know that this taste is corrupt, and that the beard is a Sunnah (definition)," is sufficient to invalidate his erroneous perception of himself, and that this is from waswasah (whisperings). The cure for this problem is complete disregard for these whisperings, and the firm conviction that they are delusions with no reality. One must repent to Allah for abandoning prayer, and know that the legislative dislike for sins does not contradict the natural inclination towards them; therefore, committing a sin is not an act of disbelief.