Studying the various religions, in all times (and regardless of the phase of religious understanding in which they are placed) we notice that there are certain basic concepts that are the same in all religions. All religions speak of the One Reality. The differences between religions are mainly interpretative and linguistic.
1) In all religions it is stated from the beginning that the Ultimate Reality (which is always considered Undefined, Incomprehensible, Infinite, etc.) constitutes the Background of the Phenomenon of Existence and all its varieties. The Absolute, Being, etc. It precedes all existence and all existence refers to It and can only approach it experientially. It is not simply a general idea to which thought reduces all beings - this general idea is a construction that follows thought and has nothing to do with the Objective Reality that posits it at the beginning.
2) Every being (every consciousness that feels that it exists) either identifies with, or refers to, the Ultimate Reality. Being emanates from, depends on, and is in relation to the Ultimate Reality.
3) Because of the existence of a relationship between the Ultimate Reality and any consciousness, communication arises not only as an existential necessity but also as a vital activity and as an existential destination.
4) The Ultimate Reality is considered by each consciousness (each subject) as a Supra -subjective Reality, i.e. an Objective Reality, which the subject approaches when he transcends all subjective, external activities and sinks into his Deepest Objective Being. The Deepest Objective Being of all existence is identified with the Ultimate Reality. This is where all meditative practices, spiritual exercises, etc. are founded.
5) Completeness of being in the context of a religion means Experiencing the Ultimate Reality (whether we think of it as identification with the Ultimate Reality, or as a union, or in any other way). The state is defined as enlightenment, deification , consummation, completion, etc., (all of which mean the same thing).
6) Experiencing the Ultimate Reality reveals to beings who achieve this that there is only One Reality from which they are never separated. The adventure through the universes, invisible and visible, is subjective which becomes, due to the absorption and weakness of the subject, objective. Illumination reveals our true relationship with phenomena.
These general concepts exist in all religions and where a religion seems to depart from the norm this is probably due to the interpretation promoted by its representatives and not to the Truth that the religion is trying to approach.
However, let's not forget that all religions are only interpretations, i.e. indications of the Truth, not the written Truth. We must experience the Truth they indicate. Truth does not belong to the space of thought, it is not formulated speech, words.