Is complete acceptance of the esoteric interpretations of the ancient holy texts fallacy?

These interpretations, mostly considered New Age, appear to hold some probable truths as to the mindset of the ancient authors, however, in my opinion, not necessarily of reality or future events. I think these also require a substantial amount of 'faith' and aren't fully based upon empirical evidence. Firstly, there are no original manuscripts available to us and those copies we do have has revealed differences by various scribes like spelling, deletions and interpolations. Many of these esotericists base their interpretations on word play using language other than that of the texts themselves, and the extraction of partial passages by which to form a conclusion and / or reasoning. Esotericists predict the dawning (enlightenment) of the age of Aquarius, upon the whole of earth in accordance with biblical astrotheology, a time when the world will finally understand and behave in accordance with its Oneness with all life and the universe. Some, like Bill Donahue, propose the number of the beast (666) is the number of man (6 electrons, 6 protons, 6 neutrons) which are the basis for everything in the Universe and the particles of an atom, which he also correlates with the esoteric understanding of the first man Adam. Additionally they posit eternal life and / or reincarnation is what's to be understood and accepted based on the claim that we are made of photon energy and the fact that energy is neither created nor destroyed. My understanding, admittedly limited, is that we are made of matter, matter is made of atoms, atoms are made of particles such as electrons, protons and neutrons and our cells emit biophotons that appear to be linked to our body's clock and the rhythmic fluctuations of our metabolism over the course of the day (Dr. Popp; Biophoton Theory). I'm pretty certain that as far know, like all energy (electrical, kinetic, sonic, etc.) the body's energy eventually becomes heat energy (entropy?). The energy we “carry around” takes the form of chemical energy like fats and sugars. When our nervous system creates electrical energy we lose an equal amount of chemical energy. So, rather than being energy itself, life is more about moving energy around from one form to another and when we die this energy is either transformed into heat energy or absorbed by other organisms. However, this doesn't mean to say these photons were within the atoms that make up our bodies to begin with. Unless we are only rediscovering what was already discovered in antiquity, these texts were written long before these particles and this biological information were ever realized. So I think it stands to reason that many are assuming the ancient minds knew this stuff without any evidence of that and accepting such claims as reality is fallacy.

If by esoteric we mean that there is a correct understanding and only a small group actually understand it (like a very specific area of science or technology), then we are not dealing with a fallacy. However, people often claim something is esoteric when they think they have special knowledge, but really don't. In the case you describe, that is what is likely going on. A more obvious example of this is glossolalia or speaking in tongues. There are a few people who claim to know what people are saying. If we are dealing with true knowledge, we can have several of these "translators," separate them, and have them all translate the same message. What we find instead is mixed messages, most of which comprise generic platitudes (God loves us, be kind to one another, etc.). Rather than fess up to the fact that they are all likely wrong and deluding themselves, each claim that the other is wrong, and they are right. We see the same thing with "esoteric" interpretations of any text (not just holy). Only the author(s) know what they meant and the real meaning behind the words, and if the authors are anonymous, dead, or in the form of gods that don't make public appearances (outside of grilled cheese), then the esoteric claims will persist.

I don't know of any formal fallacy here, but believing in people's claims of knowing esoteric meanings does show a failure of reasoning where no evidence is available.