Most religions use drugs in some way during their practices. This is to encourage irrational thought and help convince themselves that their superstitions are true. This is most obvious in primitive religions where the practitioners enter into a fully intoxicated state and experience hallucinations. These hallucinations they assume to be divine in origin. As well as drugs, many other techniques are used by religions and cults in order to discourage rational thought, such as repeated chanting and/or the telling of hypnotic stories.
You might want to rethink this a bit. Observational studies of the use of hallucinogenic substances by various tribal communities suggest that, in at least some cases, the user is able to acquire certain factual information that is verifiable. For example, certain tribes claim these substances allow them to communicate with spirits who might teach the user something about botany or spirituality. Referring to 'botany' as an example, it's also been documented that scientists in general can't figure out why some of these tribes seem to have so much understanding of botany (e.g. which plants are poisonous, which are medicinal, and which ones you can mix together to effect a certain reaction). A vast amount of knowledge about pharmaceutical ingredients used in the Western world comes directly from tribal knowledge -- that is, Western scientists frequently visit these tribal cultures to learn from them.
Can you seriously think that drugs are a good thing??? 
