Firm belief is a strong CONVICTION or set of beliefs that are held with certainty. It can be expressed in different ways, such as CONVICTION, DOGMA, and FAITH. CONVICTION is a strong belief or opinion that is held with confidence and is often based on evidence or personal experience. DOGMA is a set of beliefs or principles that are accepted as truth without question or proof. FAITH is a strong belief in something that cannot be seen or proven. All three terms can be used to describe a firm belief.