How does Unitarianism bring about spiritual transformation?
Yet the Unitarian tradition I believe does offer some spiritual guidance on going deeper. I've identified a few of these ways below, in no particular order. These techniques may not be unique to Unitarianism (indeed most spiritual techniques are universal) but they are distinctly Unitarian, though overlapping with much else.
The Unitarian tradition has often said that the Divine is within: "the realm of God is within" Jesus said. What this means, crucially, is that there is not some book or teaching its necessary to get hold of to understand the nature of reality. Truly looking within (deeper than the superficial ego) we can find God. Someone can go a whole life without hearing the gospel or the dharma and still "get it." Although for most of us, having teachers helps, but only in pointing us back to ourselves.
Communion with nature
Whether in the form of Transcendentalism or paganism Unitarians have always found God in the natural world (or found that God IS the natural world). Going to church doesn't make you a Unitarian, you have to go to the forest too. This is one of the most reliable ways to receive spiritual refreshment and transformation.
"All truly profound thinking becomes religious" said Albert Schweitzer. The struggle to work things out, to explore religious questions, to explore the universe is itself a spiritual practice. Doubting may even be more spiritually useful than believing, as doubting suggests a process, while believing is a static state of affairs. The divine is found in deep thinking.
Loving the world around you
This spiritual insight is deeply rooted in the Christian tradition, though it isn't always acknowledged as such by Unitarians. "How can you love God without loving your sister? You can't." Whatever highfalutin spiritual techniques you have, even if you spend hours meditating, it's all for nothing unless it leads to love for others. Love for others is a spiritual practice, and it deepens other spiritual practices. Love extends beyond the purely personal to include the political.
Spiritual transformation is brought about by a process of integrating every part of the human self: the soul, the mind and the body. You should not leave your doubting mind or your sexual body at the door of the church as you do something for your soul. All parts of ourselves need to be accepted and integrated. It is spiritually harmful to deny a sexual orientation or a doubting mind.
It is only by truly and deeply listening to the other (and not just to ourselves) that we can hear the voice of God. A process in which we speak honestly, and are heard, and listen fully to an other creates a place where we meet the divine. This is a challenging process that we're not always good at. But perhaps this is a spiritual practice that we need to take on more fully.