".......The yogi says there is a great danger in stumbling upon this state. In a good many cases, there is the danger of the brain being deranged, and, as a rule, you will find that all those men, however great they were, who had stumbled upon this superconscious state without understanding it, groped in the dark, and generally had, along with their knowledge, some quaint superstition. They opened themselves to hallucinations. Mohammad claimed that the Angel Gabriel came to him in a cave one day and took him on the heavenly horse, Harak, and he visited the heavens. But with all that Mohammad spoke some wonderful truths. If you read the Koran, you find the most wonderful truths mixed with superstitions. How will you explain it? That man was inspired, no doubt, but that inspiration was, as it were, stumbled upon. He was not a trained yogi, and did not know the reason of what he was doing. Think of what the good Mohammad did to the world, and think of the great evil that has been done through his fanaticism! Think of the millions massacred through his teachings, mothers bereft of their children, children made orphans, whole countries destroyed, millions upon millions of people killed!..."
Swami Vivekananda . CW I p 481-3(Raja Yoga)
Indeed, a little knowledge is a dangerous thing... but even more dangerous could be what one thinks as knowledge, but that lacks training and practice..