What do you know with certainty?  Whatever came to your mind just now, can you truly know it is true?  Would others know it as true?  Is the sky really blue?  Is it blue always?  Is it possible that your perceptions may be skewed?  Be careful when you believe something so strongly that you dig in your heels.  The left brain wants to justify beliefs at all costs.  That is what it does, whether or not the belief is true.  If it is true for you, but not for another, then beliefs are changeable, as is truth.  The one Truth is Be-ing.  You ARE.  That is all.  All else is added for the learning and the growth.  Question your beliefs and grow as you test them in your heart.