The Bible is the source of authority for what we believe and practice.
All Scripture is God-breathed and is useful for teaching, rebuking, correcting, and training in righteousness. 2 Timothy 3:16-17
For prophecy never had its origin in the human will, but prophets, though human, spoke from God as they were carried along by the Holy Spirit. 2 Peter 1:21
Sanctify them by the truth; your word is truth. John 17:17