Mormon uses the concept of opposition to create a great polar divide. God stands on one pole as the representative of Good, and the devil stands on the other pole as the representative of Evil. These two forces represent the most essential of all diametric oppositions. There for, all that is good must come from God, by definition, and all that is evil must come from the devil, by definition.
Of course man has agency, but in this symbolic system, Mormon is placing man directly in the middle of the symbolic opposites. In Mormon’s imagery, man sits in the precise balance of good and evil, and it is man’s agency that will listen to the “enticings” to move toward one pole or the other.