Okay, I can't stand the 'cleric of a cause' clause (say that five times fast), but I'll leave that aside for a moment. To my understanding, it's only there at all so that people can play clerics without having to roleplay the trappings of religion, if for some reason they don't want to.
However. This does not, to my mind, cause the cleric to become definition-B secular. (A cleric is of course never definition-A secular.) It merely broadens the idea of what it means to be of or related to deity, divinity or religion. If your adherence to and belief in an alignment is enough for you to manifest 'divine' spellcasting powers, then there is something 'divine' about such adherence; therefore any character who adheres to a 'cause' is no more secular (def-B) than one who adheres to a religion.
Thus, paladins are not secular (def-B).