An avowal is an affirmation of the truth of what you believe. It’s an honest admission. An avowal is a way of owning up to or declaring something.
To avow is to acknowledge or claim something. An avowal is an example of this. Saying the Pledge of Allegiance is a type of avowal because you're stating your belief in the United States. Marriage vows are a type of avowal because you affirm your love and loyalty to someone. Prayers that state the existence of God are avowals because you confirm your faith and belief. People only make avowals for things they believe in wholeheartedly.