"If anyone is willing to do His will, he will know of the teaching, whether it is of God or whether I speak from Myself." (John 7:17)Now, isn't that a little backward? Do we know His teaching is from God and then will to obey, or do we will to do His will and then know it is of God? Do we know the truth and follow it, or do we first determine to follow the truth and then know it?
Jesus seemed to think that a prior commitment to obedience was a prerequisite to knowing that He was from God and His words were truth. Not how we ordinarily think about it. But it does go a long way toward explaining why His truth gets rejected, even by some who claim to follow Him.