I've heard many people talk about having insightful and profound spiritual experiences through the use of psychedelics. This is certainly a potential with such drugs, but this misses the real point; the core of such benefits usually sought by trippers is the fact that psychedelics alter our approach to the world around us in such a way as to sometimes provide that gentle push - or shove - in the right direction needed to fully attain an insight - about our world, our relationships, or ourselves.

I just stumbled upon an excellent article discussing how psychedelics can help to drive home certain insights:

Insight « Michael Vipperman