My thoughts are not your thoughts, neither are your ways my ways, saith the Lord. For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts. Man's thoughts are open to the view and knowledge of the Lord. To his prophets also this power is given as occasion requires. Christ frequently exercised his power to read the thoughts of those among whom he ministered.
Evil thoughts are sinful.
They are an abomination in themselves, and they lead to further wickedness. Evils are not committed until they have been thought out in the heart. For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders, Thefts, covetousness, wickedness, deceit, lasciviousness, an evil eye, blasphemy, pride, foolishness. Men are what their thoughts make them. As he thinketh in his heart, so is he.