Totalitarian: Ideology or religion that is pretended to have final answers to many important human questions and problems and that is pretended to be thereby justified to persecute persons who do not agree with the ideology or the religion.
This is the usual form that every human ideology assumes - religious, political and otherwise, with science as the almost only partial exception.
The reason for the first property that defines a totalitarian attitude is apparently in part political and in part zoological:
One very important end ideologies and religions serve is to provide a human social group with a set of shared agreed upon supposed truths for the group and supposed ends of the group, and it is simply convenient and also seems to feel pleasant to most humans if these supposed truths and supposed ends simply are taken to hold for everyone, or at least for everyone who has the fundamental decency and human excellence of belonging to Us.
The reason for the second property that defines a totalitarian attitude derives from the first property plus the fact that ideologies and faiths of a social group serve to define and defend the group's territory and practices.
It usually takes the form of forbidding to think or argue critically about the fundamental assumptions of the religion or ideology and of insisting that following the religious or political authorities is morally good and socially rewarding, and that not following the religious or political authorities is morally bad and socially punishable.
One important reason that so many ideologies and faiths take a totalitarian form is probably the social nature of human beings, that makes it natural to maintain the pecking order of a group - who is entitled to what in the group - by correcting, repressing or casting out any member of the group that deviates from the average of the group (unless already a leader). This usually is claimed to happen "in the interest" of the deviating or different individual, and is called scapegoating (at least when goats give in to the same beastly impulse).
Totalitairian ideas and values are very widespread, and usually take the following general form in practice, if not as clearly outspoken:
Our Belief is the Only True Belief and Our Believers are the Only Good People, and everyone who does not believe, or do, or feel, or look like Us is inferior (sinful, bad, damned, bound for hell, fit for a concentration camp, and in any case not a proper well-thinking, decently feeling, morally behaving follower of Our True Belief, and hence certainly not comme il faut).
The myth of the Chosen People of the Lord is not only biblical, but seems to be an article of zoologically and hormonically based faith of the the individuals of most social groups: They - Our Kind Of People - and only they are the best, true, real, human beings, and every one who is not like they (We) are is not really good (and therefore may or should be persecuted by authority of the Lord or the Leaders of the group).
The supposed truths and values of any religion or ideology tend to be absurdities according to the common sense of whomever does not have the religion or ideology. And in general Voltaire's sharpwitted dictum applies here: "If we believe in absurdities, we shall commit atrocities."
Indeed, the main factual, moral and intellectual problem of virtually all religions and political ideologies is not that most of the key theses of the religion or ideology are nonsensical, false or not properly based on evidence, but the fact that these key theses are used in a totalitarian fashion.
For there is no danger in fairy tales, myths, fiction and wishful thinking as long as those who indulge it are clearly conscious that their ideological stories for the most part are just that: fairy tales, myths, fiction or wishful thinking, or at least as long as those who believe in an ideology or religion remain clearly aware that they may be mistaken, and that everything one cannot prove in a rigidly logical and mathematical way from evidently true premisses therefore and thereby cannot be imposed on someone else as what they are supposed to believe in and hold true.
Religious and political fairytales, myths, superstitions and wishful thinking are rarely understood and defended by their believers as if their belief is one possible hypothesis amongst many others about how people should live together and think rationally, but almost always are understood and defended by their believers as if their belief is The Truth, All Of The Truth, and Nothing But The Truth - and especially where this is clearly not so.