Most legitimate religions are human institutions surrounding higher spiritual truths. They are put in place with their systems of belief to support those higher truths, to teach them to other, and so forth.
Something occurred to me this morning after meditation. These claims that these things are not "in scripture", is completely a bogus, red-herring distraction. Is it Christian? Yes, of course it is! People who are Christians have and do practice these things in support of their spiritual path within the Christian lineage. Lineage is the operative word here. If you recall the passage in the Bible where it says we are "built upon the foundation of the apostles and prophets, Jesus being the chief cornerstone"? This misguided, modern notion of "fundamentalism" is false. What they are doing is a form of modern Retro-Romanticism, imagining this idealized past when everything was pure and true. This mythologized notion of getting back to the 'basics', is nothing short of just a simple, misguided nostalgia of a fictional reality.
Let me explain myself. Any religious lineage evolves and changes over time to meet the needs of a growing need in a growing world. The world is not stuck 2000 years in the past, and Spirit is not static. Neither should the church be. Even IF meditation practice was adopted into the Christian lineage as something recent, it is still a legitimate Christian practice if it has been integrated into the Christian lineage! Of course it is historic, but it doesn't matter even if it wasn't. When it say we are built upon that foundation, the operative word is "built". There are new structures being built all the time!
This myth of fundamentalism envisions there is no building whatsoever, no creative choices allowed, no variations, static fixed, and flat. Flat on the ground level. No building at all. It is foundation only, and a foundation that arose to meet the needs of a culture 2000 years in the past. To live then, in this imaginary reality of the "pure truth", utterly fails to understand the truth of the dynamic nature of faith in an evolving world. The church is "built", not finished 2000 years ago.
Now, I can continue in this, but my point is it is entirely legitimate to have new insights, new understandings, etc, that "build" upon the foundation. As as they build upon that, it is in fact Christian. It follows from the lineage. But that is not good enough for fundamentalists who want to tear down structures they don't understand which they find themselves unable to relate to. "It's not in the Bible," is actually not the litmus test at all. Is it consistent with the Spirit of Truth is. "The letter of the law killeth, but the Spirit maketh alive." Why? Because it lives, and breathes, and grows, and evolves, spreading out touching and being part of the world of the present, not a mythological imagined nostalgia fictionalized past.
/rant