We can't know the mind of god only what he tells us about his demands, intentions, attributes etc. Scriptures are usually the source if what god has prescribed and demands etc, or men sent as prophets. Therefore the question arises which scripture is gods word, that's the journey of discovery, test them all of their claim.
Second way of knowing god so to speak in a limited sense is through philosophical and logical deductions. Combine them with science and scripture and you get a good picture.
But to know the mind of something infinite, all knowing, omniscient, omnipotent, all encompassing entity, is beyond our limited capacity. Hence why god would send his instructions via man, something recognisable and words (language) something that separates us from other life forms and the best way to preserve and spread knowledge is literature. If a book claims to be gods words, it will also carry his attributes, ie mistakeless, perfect, inimitable, etc etc etc.