The Satan is a created being. He was not given a free choice of his own... he was created for a purpose and he does what he was created to do. God said, “I created both good and evil”... and why did God create evil so that we would know good... Isaiah 45:7 “I form the light, and create darkness: I make peace, and create evil: I HaShem do all these things” There is nothing here but God and His Name... mankind is given a free choice along with an evil inclination and a good inclination to apply your free choice too... if you apply your free choice to your good inclination and do what is right according to the Torah for the sake of heaven because God commanded it you will receive a portion in the world to come (heaven).... if you apply your free choice to your evil inclination and reject the Torah you will create your own gehinnom (hell)... the Satan has no control over which inclination (good or evil) you chose to apply your free choice too. The Satan only accuses you before God of the choices YOU made... it is not the evil that God created or the evil the Satan causes, but it is the evil YOU created from ignoring the Torah to satisfy your ego and to please your physicality. God is not evil and the Satan is not evil... YOU are the one who creates the evil out of your free choice, which allows YOUR evil inclination to cause YOU to ignore the Torah... for the sake of self alone.