So, you think your mind is your Final Authority?
Well, if you are honest you will have to admit that you have been wrong about something in the past. This proves that you make mistakes. Then you must admit that your Final Authority is flawed and can not be trusted 100% of time. To base your core beliefs on your mind is a dangerous prospect.
Here is what the Bible says about your mind.
Psalms 94:11 The LORD knoweth the thoughts of man, that they are vanity.