The term 'basic belief' can refer to four different concepts: Theism (6 letters), TENET (5 letters), CREDO (5 letters), and Deism (5 letters). Theism is the belief in a single God or gods, while TENET is a principle or belief that is held to be true. CREDO is a statement of faith or belief, and Deism is the belief in a higher power without necessarily believing in any particular religion. All four terms refer to a fundamental belief system that guides an individual's life.