Much valuable instruction on the Wahhabis=Unitarians point. Kinglake apparently knew his stuff.
Among the more succinct reader replies (but many thanks for all, succinct or otherwise):
Derb—Modern Unitarians–more properly, Unitarian Universalists–think that anything goes, but this is an inheritance from their Universalist strand, not their Unitarian strand. Before the two strands amalgated, Unitarians were all about the oneness of God and a rationalized, clean religion untouched by sentimentality, tradition, ritual, and so on. Your writer probably meant that Wahabis, like Unitarians, were big on God being one and big on expounding a religious system devoid of human touches.
And:
Dear Sir—I suspect the answer to your bleg on the Corner is that the 1830s writer was using the term Unitarian in its original sense, that of a believer in a single God, without brother or son or other Persons in a Godhead. This is of course the true Muslim belief, and those who, like the Wahhabis, are most ardent in this principle, can be accurately stated to be Muslim Unitarians.
“The Wahhabis aggressively oppose any tendency to provide what they see as reverence or worship to saints or holy men, in many cases destroying their graves and shrines. This is in many ways their largest single difference with other sects of Islam, and it grows out of their tendency to take the Unitarian principle to its logical conclusion.
“BTW, the present Unitarian Universalists are quite different from the Unitarians around in the 1830s, who were merely liberal Christians. They followed the logical path of liberal Christianity, becoming more and more ‘liberal’ till they wound up believing essentially in everything and therefore in nothing.