An interesting intersection of politics and religion. There is no way anyone would be able to make a reference like this today. Not because the separation of religion and politics is so stark, but because no one would understand the reference.
1. prop. An inhabitant of Adullam.
2. a. A frequenter of the cave of Adullam. fig. A nickname applied in 1866 to certain members of the British House of Commons, who seceded from the Liberal party then in power, from dissatisfaction with their attempt to carry a measure of Parliamentary Reform. The name originated with an expression in a speech by Mr. Bright; see quot. 1866¹. More widely, a member of a dissenting political group.
b. attrib. or as adj. Of or pertaining to the seceders of 1866. Also transf., esp. of other political dissenters; radical, unorthodox.