Actually, interpretation is based on evidence and minimum amount of facts.
Answer:
There is alredy a treaty called Geneva Gas Protocol that banned the use of these weapons
The Geneva Gas Protocol, in full Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare, in international law, treaty signed in 1925 by most of the world’s countries banning the use of chemical and biological weapons in warfare. It was drafted at the 1925 Geneva Conference as part of a series of measures designed to avoid repetition of the atrocities committed by the belligerents in World War I.
The problem is that it is difficult to implement but a good measure would be very high fines to the countries that produce or stockpile these weapons.
We can name three big reasons here.
1. The conversion to Islam in the early age was not something sudden and it did not mean that the previous religious convictions of the population were abandoned. The way it worked was that the Islamic practices were integrated into existing religious systems.
2. Second one is the traveling religious men who went and spread the faith. Wondering holly men were peaceful and were not perceived as threats.They were educated and often were healers. This allowed them to intermingle in the other societies and be their connection to the Islamic world.
3.The renewal movements or the reform ones were created in response to this intermingling of Islam with other religious doctrines. They wanted to return to the true faith and keep Islam pure. They wanted to purify it from foreign influences.