If that were the case, then you have a real problem with St. Paul of Tarsus. His life helps answer Sunstone's excellent question in the OP I think too, so let me try and kill two birds with one stone
His authentic Letters are the earliest Christian documents that we posses; the sayings and life of Jesus were at that time chiefly passed around orally or through primitive documents such as the hypothetical Q source underlying the synoptic and the Passion narrative and Signs Gospel thought to underpin the Gospel of John's traditions.
He never knew Jesus personally. His conversion to Christianity rested around a profound religious experience whereby he beheld, not Jesus the mortal man, but the Living Son of God. Paul saw a blinding light on the Damascus Road, and then an invisible voice spoke to him (Gal 1:13-17; Acts 9:1-9).
According to Galatians, he tells us that immediately after this episode he fled to the deserts of Arabia, obviously to contemplate what this experience meant and discern his new path in life.
He then began to have "visionary" experiences such as one in which he realized that the church was the "mystical body of Christ" (1 Corinthians 11) with each believer being part of it.
His spiritual journey developed from this into full-blown mysticism. In 2 Corinthians, he lets slip that his ability, although never having known Jesus, to compose inspired literature and teachings that would become Christian scripture, stemmed from a profound experience in which he lost conscious awareness of both himself and creation, a characteristic example of "non-sensuous" mysticism. He explains how he was, “
caught up to the third heaven — whether in the body or out of the body I do not know; God knows…. [And was] caught up into Paradise and heard things that are not to be told, that no mortal is permitted to repeat” (2 Cor 12:1-4).
Being unable to describe adequately with words what one has "experienced", is a classic example of ineffability, one of the qualifying signs of a mystical experience. There are states one will never understand alone with the rational human intellect however one can experience it. Thus two later Christian mystics noted:
His lack of awareness as to whether he was "in the body or out of the body" indicates the breakdown of his surface intelligence and a lose of awareness of himself of a distinct "I".
This is confirmed by his famous declaration in Galatians: "
It is no longer I who live, but Christ who lives in me" (
Galatians 2:20).
A later Christian mystic, from the Syrian Orthodox Church, had the exact same experience (and I use his as my signature quote):
John of Dalyatha in one of his letters refers too, "Paul, the philosopher of the Spirit" as his inspiration.
As Evelyn Underhill, an early 20th century scholar of Christin mysticism noted:
Last of all, St. Paul's experience of this state which he calls the "third heaven" was described by another medieval Catholic mystic, Jacapone da Todi, who claimed to experience the same:
The upshot of my argument is this:
No, religious experiences and mystical experiences are not necessarily the same. Atheists, such as Sam Harris, can lay claim to mystical experiences and many religious believers have had none.
Nevertheless, religious experiences can "start" off a journey that will eventually lead to mysticism, as happened in the case of Paul.
Therefore the majority of history's mystics, although by no means all, have usually been affiliated with religions.
Also religious people will often relate their mystical experiences to their religion and use terminology applicable to it in their descriptions thereof.