Understanding is everything
A belief system is often visualized/expressed as a number of pillars which taken together form the core of that system of beliefs. I will also use the analogy of pillars, but in exploring that analogy I have realised that in my conception of my beliefs there does exist something larger than the pillars and the practise itself.
All of my beliefs, some of which fit the analogy of pillars, point to one thing, a single purpose which gives context to the existence and practise of those beliefs. To understand.
I believe the answer to the question of purpose in my life is simply: To understand In this I find a balance to the existential angst that arises from too vague a purpose, and the fragility that seems inevitable with too narrow a purpose.
I expect that on some level this idea occupies the same space in my mind that God might in a person of faith.
This purpose therefore is not one of the pillars of my beliefs, it is the reason for those beliefs.
A closing note: I think there exists a reasonable criticism of this purpose, as written above, that it may in fact represent a tautology, ie my purpose is to understand my purpose. This is, I believe, a defect of my writing, not of the idea itself, and is exacerbated by what I believe is an inherent kinship of these two ideas. That is, on some level, understanding is purpose, and purpose is understanding.