I suppose the meaning of "bigot" and "dogma" are more in the connatation that the definition. It's the manner, the tone, the attitude in which someone expresses his "disapproval" more so than the disapproval itself---blunt, rude, insulting.
A "dogma" generally applies to a religious tenet and is therefore generally mystical, "transrational", though I'm sure many religionists would prefer to think of their tenets as "rational". In any case, it's definitely acquired a very pejorative sense, deserved or not.
Disputants will sometimes declare the opinion/conclusion/axiom of each other as a "dogma". " I have 'axioms"' you have 'dogmas'". It's ultimately just empty, frustrated rhetoric. But, like "bigot" there may be an attitude, a manner, a tone in which a statement is uttered, is "dogmatic".
I think the point at which a principe might be reasonably called a "dogma" or a person with a moral position or dislike a "bigot" is very problematical, and exploring that should involve as much self-control as we can muster, without tossing around empty pejoratives.
I look at these questions from a radically agnostic perspective. (Though I am a radical agnostic, I still have convictions/beliefs/principles. I now and then try to "argue" for them, but make no claim they're a priori true or proven.)