"[One] way of making the distinction, if we don't look at logic, ... is that what marks a kind of philosophy as religious is that it has some sort of reliance on authority. The obvious one would be a supernatural god. If you depend on God to be the determiner of truth and falsity, rather than argument and logic, then that's a form of religion. It would also be a form of religion even if there were no God. If you depended on a text, a particular text, or on a particular tradition, if you insisted ... whatever is true comes by a kind of unverifiable experience, a revelation, or a vision, or some mystical experience that cannot be evaluated, criticized, or studied by science, then I would call that religious.
And what I would call philosophy, is anytime the content of thought is the result of discussion, and exchange, and contending, if the schools are disagreeing and as a result they make intellectual progress; that is they move from less adequate to progressively better theories, because the arguments make them reconsider and re-evaluate and make progress. Then I would want to call that philosophy rather than religion because it's free from authority, and it makes progress through discussion."
I'm not sure I agree with him. Unitarians would seem to fall between his definitions. Unitarians today believe that although we may develop spiritually within a particular faith tradition, "such development is greatest when the believer is in active and critical dialogue with it." (Cliff Reed) This is the antithesis of the traditional view of authority, which requires unthinking submission to a particular creed or set of beliefs. It means that Unitarians can be open to inspiration from whatever source it comes - in the natural world, in the sciences and arts, in our work and friendships, in our sorrows as well as in our joys.
Our view of authority has modified over the centuries, from a dual belief in reason and scripture, to our current position that "each person is his or her own final authority in matters of faith." (Cliff Reed) The authority of individual reason and conscience is held to be supreme, but it is important to be a member of a religious / spiritual community to which you can bring your questions and your doubts, in the sure knowledge that they will be met with a broad, questioning tolerance. The interplay of individuals' beliefs is one of the great strengths of a Unitarian congregation - the bouncing of ideas off each other means that we can never be complacent about what we believe. It is stimulating to belong to such a community, but can be very hard work. Nothing is set in stone, and each individual is responsible for keeping his or her mind open to new ideas, so that our faith can grow.
So is Unitarianism are philosophy or a religion? I think it is both/and, rather than either/or, and stronger for that.