This is the question addressed by William Wildblood in a recent blog post to which I have contributed a comment:
It is an important observation that modern spiritual people are indeed notably left/ liberal in outlook; because it leads to the recognition that they are left/ liberal with greater intensity and conviction than they are spiritual. Their spirituality is eclectic, flexible, changeable - their leftist politics is dogmatic, solid and often fanatical. It is easy to see which they are most serious about.
I became interested in New Age type spirituality from the late 1990s (i.e. before I was a Christian), in the sense of reading some of the recent and still active US writers. Up until then I had read a great deal of CG Jung, upon which much of New Age is based; and a lot of Colin Wilson - who never quite fitted into this category but overlapped with it. But from 1998 I read John Hanson Mitchell, James Hillman and some of his 'disciples' such as Daniel C Noel and Thomas Moore; and a smattering of others across the field, including most of the best known writers.
At that time I was a libertarian centrist in politics - and would have been a Republican if I was American; and I noticed in interviews and personal reminiscences that these and other writers came across as fanatical Democrats of the most partisan type for whom even the mildest libertarian or conservative ideas were demonised - and on the other hand openly advocating seedy, corrupt, dishonest careerist Democrats as if they were spiritual exemplars leading the world to a higher future (e.g. the likes of Al Gore!).
And New Age writers were typically, almost universally, utterly in thrall to New Left concerns - and structured their theories inside such a world view. For example Ecopsychology (look it up) was supposed to be a fundamental biological-spiritual perspective on the earth - but in practise made all kinds of recent and ephemeral leftist socio-political assumptions - and seemed to operate as a Left Wing pressure group.
A book that I read with great attention - the Soul of Shamanism, by Daniel C Noel - structured its entire analysis and argument within a context of politically correct 'sensitivity' to the imagined perceptions of 'indigenous peoples' - with an intensely moralistic inflection to this demand that stood in complete contrast to the 'amoralism' of the spirituality being advocated. I mean, those individuals who were deemed to have behaved disrespectfully to the supposed sensitivities of American Indians (by 'appropriating' their spiritualities and adapting them for modern Western usage) were 'damned' pretty strongly!
This happened so often that I eventually realised that it was structural to New Age spirituality; and undercut the depth and validity of that spirituality. The New Age was, in fact, being led by people whose own spirituality was at best shallow and insincere; and at worst merely a front for their primary aims which were Left-political.
Nowadays, I see one of my main tasks as resynthesising spirituality with Christianity, in a Christian frame - i.e. with Christianity as primary but spirituality given full value as a necessary modern priority.
And in this task I realise that very little of modern spirituality is relevant, because very little is worthwhile. Those authors who are worthwhile are those for whom politics is a very secondary concern - the likes of William Blake, ST Coleridge, Rudolf Steiner, Owen Barfield; and more recently William Arkle, Colin Wilson, Jeremy Naydler, and William Wildblood himself.
By no coincidence these are also those whose spirituality is honest, sincere, often deep: and primary.