Welcome to the forum coolguyalex.
The interests you speak of I believe are shared by quite a few of our members here, so I'm sure you will get some nice discussions going. I myself was looking into some similar things a while ago - asking myself if entheogens and the origins of different religions or at least early practice of different religions were directly linked to each other. According to the sources I've found... I still am undecided about it.
Of course in some cases like shamanism it's quite obvious that they were used, but in gnosticism? in christianity? budhism? most modern members of these faiths would vehemently negate this, I suspect. However, some of the symbolism used in these belief systems can sound compellingly like indications of entheogenic use or altered states, etc.
I think right here is where we have to stop a second and consider that altered states as well as mystical experiences can be brought upon very many things that are not psychedelics - such as trance (through dancing or drumming...), meditation, illness, NDE, dehydration, sleep deprivation, psychosis, spontaneous... etc.
So I remain undecided, while I do enjoy musing the topic. So let me know what you've come up with so far in your investigations
In any case this doesn't keep me from believing that now at this point in time entheogens have great potential for individuals to assist them in their pursuit of spirituality and growth, creativity, psychological integration and exploration etc. And this IMO can very successfully be combined with other spiritual practices.
take care and have fun exploring the nexus and your own mind