While looking for the source of an obscure responsive reading, I came across this little service book: Mission hymnal of the Unitarian Laymen's League. Despite it being undated, and Internet Archive dating it to 1900, it is in fact later. Unless the Unitarian Laymen's League had the powers of time travel, as it includes a hymn dated August 9, 1929. (It predates Hymns of the Spirit, 1937, for closer dating.)
Its tone is serene yet vital: a religion of rest of dyspeptic captains of industry, I wouldn't half guess. Its purpose: to help establish Unitarian preaching stations, and more spiritually developed men. Yet, at first glance doesn't seem to suffer the excesses of "muscular Christianity" from the generation before.
Two interesting points:
- It has a hymn by a Universalist. "We praise thee, God, for harvests earned" by John Coleman Adams. (A God-free version exists in Singing the Living Tradition as "Our praise we give for harvests earned," #294.)
- The directions for prayer have a certain Unitarian resonance:
You say, however, "I do not believe in prayer." Even so, this does not obviate the necessity of daily spiritual exercise. Retire every day into the silence of your own thoughts, there commune with the highest you can possibly conceive.