You can release a gas around your body that breaks down certain neurological connections in the brain which cause their established worldview to completely collapse. While they still retain their memory what they believe in and how they interpret the world is completely reset. A doctor hit with the gas would still remember all their memory of practicing medicine and their skill with the tool but could now believe that a banana can cure a stab wound or any other ridiculous notion that a child who doesn't know any better would believe in.
Shortly after being hit with the gas they are susceptible to being influenced by whatever form of narrative that is first provided to them. A deeply religious man could become an atheist or follow Mickey Mouse as his new god, a bigoted person can become an incredibly open-minded person and vice versa, ect
As long as they are provided a replacement narrative they will in everything you say or if left to their own devices believe in whatever their mind fancy.