The point of Rav Nahman that Satan is dressed in mitzvot [as it says in the first Torah lesson in the LeM] is this: The mitzvot are not goals in themselves. They are to bring to natural law. Laws that are recognized by means of Reason. This is the opinion of all rishonim. This is also clear in the Gemara itself. In the Gemara we find [Bava metziah page 119 side a] the sages do not disagree with R Shimon ben Yochai about the fact that the mitzvot were given with certain goals as their purpose and these goals are known. That is not the disagreement. Rather-the disagreement is if there is conflict between the reason for the law or the letter of the law,-- which one do you go by? But we do know the reason for the law according to both opinions. But almost no where in the mishna or Gemara are the reasons stated. That is left to the rishonim [mediaeval authorities].
So now we can see how the evil inclination can be disguised in mitzvot. For sometimes keeping a mitzvah results in the opposite of the intension of the law. [reasons: (1) to gain good character traits, compassion, mercy, kindness, honesty, not to slander; honor of one's parents (2) peace of the state; (3) to avoid idolatry.] [And for the religious, the result of the façade of keeping mitzvot usually results in the exact opposite of the actual reasons for them. However this ought to be qualified a bit. After all the Litvak world that follows the Gra is actually pretty close to keeping the Torah and the reasons for the commandments as well as possible. If everyone would simply be following the path of the Gra and Rav Shach I would have nothing to complain about.'
