Mystics esteem their opinions and their experience above the nature and extent of the greater authority whereby men are saved, sanctified and secured, namely the Word of God. Their obnoxious opinions defy the very ground of biblical faith because their perceptions about God are contingent upon their experience of Him, presupposing God acts in a way He has not acted and says what He has not said. Sure, a consciences mystic may try to provide a kind of biblical argument; however, his proof texts patronize the biblical attestation more than agree with it. If only they heard what they were saying, "God subjectively graces them with a special special revelation beyond and above what he has affirmed with the words of His mouth."
On the contrary, Christians affirm that God shines into our hearts the knowledge of the glorious gospel of Jesus Christ acting specially or supernaturally with the same kind of creative power he employed when He spoke the world into existence. Christians also affirm that God works through means namely the sacraments, the Scriptures, and prayer: otherwise there is not an ounce of surety that God acts in a given esoteric way as many mystics protest.