According to a frighteningly convincing and fairly recent popular science novel called The Cosmic Serpent: DNA and the Origins of Knowledge by Jeremy Narby, hallucinogens may actually get us closer to understanding religion, science, and the alleged schism between the two.
Narby is an anthropologist who tries drinking ayahuasca while he's in the Amazon rainforest. He sees giant fluorescent serpents and eventually wonders about their significance both inside and outside of this indigenous culture. Though the book could never be done justice in a single node, the conclusions are basically as follows:
1) Ayahuasca binds to neural receptors that control your vision. This has two effects - first of all, you see things that don't exist, like a giant toaster the size of a car. Second, your capability to perceive (no, not see) things that really are there vastly improves. The snakes so common across separate Amazonian tribes are actually the twisted double-helices of the giant web of DNA surrounding you all the time, transmitted through radio waves and picked up by the supersensitive receptors in your tripping brain. Part of DNA is crystalline, remember? It can amplify radio waves.
2) Information about not only form but function of molecules, cells, and entire multi-celled organisms is collected and interpreted by the shamans of the tribes, the ayahuasqueros. In other words, the plants really do talk to these people. Result: the shamans, though usually unable to fully describe why (from a molecular biological standpoint), can tell you what plants will cure an achy back or a common cold.
The moral is that certain hallucinogenic drugs are not as dangerous or pointless as western scientific culture would have us believe.