Having spent most of my life not a Christian, I am aware of how much can be provided spirituality by other 'religions' - as well as being aware that it is not enough.
My first religion was that of Higher Consciousness, of what Bernard Shaw called Creative Evolution. The idea that our human future was a matter of making our rare and best states of mind into our normal states of mind - and continuing in that same direction. This view was mine from the mid teens, and was amplified by Colin Wilson from about twenty.
The view was optimistic (compared with secular culture) but was difficult/ impossible to accomplish fully (more of an aspiration than a plan) - and left all the big things unchanged. Life might become happier, more fulfilling... but there was still age, decay, disease, bereavement, and our own deaths.
The higher consciousness view makes everything depend on the mind, will, concentration active striving - and leaves out a great deal of unconscious life.
It was exhausting, and I could never stay inside the mindset, and always needed to take refreshment in more earthy and hearty activities and aspirations - folk music, dancing, vulgarity, feasting and carousing.
As well as wanting to become a being of higher consciousness -I wanted to be absorbed into the web of life, un-conscious like a happy animal. I wanted to live in the moment, and in dreams.
This was the other religion of animism - although I didn't find a name or theory for it until I was middle aged.
For animism life was and is and always will be. Everything significant is alive, and in communication. People die only to return - we ourselves are simply returned from previous lives. Life circulates: there is transformation but no real change.
There is no meaning to this - it just is; there is no purpose to this - it just happens.
Thus animism. When in the state, briefly, all problems dissolved. But it was just like - exactly like - a pleasant dream. It did not link up with anything else. While a real animistic society is in fact full of explicit rules and purposes and explanations that are simply accepted as true - to be a solo animist in the modern West is not the same thing at all - it is to extract a part of a greater whole, and to try and deny everything except that part - an impossibility except as a brief 'holiday' from mundane life.
So... Christianity. Meaning. Purpose.
But then, I found - I continue to find, mainstream public normal Christianity is incomplete. It lacks the necessary components of Higher Consciousness and of Animism. I needed - I still need - to incorporate the wisdom and sustenance of these into Christianity.
Christianity is the capstone of a full spirituality - it is not the whole thing, nor was it meant to be.
Or rather, it was the whole thing - but because Christianity was a capstone when Christ made it: it was an addition to what went before, to what existed - Christianity was a completion of what went before - it required much of Judaism and much else that was spiritually generic to early men.
That is worth bearing in mind - because trying to live by Christianity alone (as so often urged - often with the best motivations) can be to make something black and white, thin and hard, crude and cold, thin and unsatisfying fare (mere gruel) - whereas to regard Christianity as a capstone of much else can be to feel and follow Christ's teaching as a wholly-joyous and whole-some thing.