Scripture is profitable first for teaching.
Right belief is necessary for salvation.
The power to set you free from ignorance, prejudice, error, the power of evil, and sin is in the truth, if the truth is known. John 8.32 and you shall know the truth, and the truth shall set you free. There is a connection between right belief and right practice. For as he thinks within himself, so he is. Knowing true doctrine is necessary for the right worship of God.