Complex sentence: Scientologists believe that human beings accumulate anxieties, psychosomatic illnesses, and aberration due to receiving engrams throughout their lives and that by applying dianetics every single person can reach Clear.
Split into simpler sentences: Scientologists believe that human beings accumulate anxieties, psychosomatic illnesses, and aberration due to receiving engrams throughout their lives. By applying dianetics, every single person can reach Clear.