What is the validity of the specious argument that the Creator of good is not the Creator of evil, concerning the Majus?

The assertion by the Majus (Zoroastrians) that there are two gods, one for good and one for evil, is false. This is because if the universe had two gods, its order would be corrupted, as Allah Almighty states in His Book: "Had there been therein gods besides Allah, then verily both would have been ruined" and "No son did Allah beget, nor was there any god along with Him. Had there been, then each god would surely have taken away what he created, and some of them would surely have sought to dominate over others." The universe is orderly and wonderfully made, and this indicates the Oneness of the Creator.