It came out of the Enlightenment which was in part a response to rather brutal and immoral theocratic leaderships. Theocrats claimed an authority from gods to do anything they damn well please.
Yes and no. The modern secular state came out of "The Enlightenment", but was the end of a much longer process. Basically nothing that happened during "The Enlightenment" was particularly new, just a further evolution of trends that had started in the Medieval period. The separation of church and state was a process that began nearly a millennium earlier.
Where were the 'theocracies' though? Who were the 'theocrats'? If you mean Divine Right, that is not theocracy, almost the opposite as it related to the King's 'Divine Right' to rule over the secular sphere in contrast to the Church's mandate to rule over the spiritual. It was a direct opposition to theocracy.
And while religion has been used to justify violence, in other situations, it also acted to limit it. The defining "Enlightenment" value was not humanism but "Progress" and this often took very violent and illiberal forms.
It's also not like the powerful needed an 'authority from god' to exploit the weak, they did that the world over no matter their belief system. Divine Right or Might Makes Right make little difference.
If you mean modern people can believe obsolete ideas, like creationism, because it was the best human could do before the age of reason and science and this tradition is easier than being well informed, yes.
No I mean that secular humanist types create their own mythos. They don't 'see the world as it is'.
One obvious example would be the stock myth of the "sceptical rationalist" idea that the Greeks were good secular rationalists but then came the "Christian Dark Ages" where the evil Church sought to keep people in darkness and destroyed classical scholarship as they hated knowledge and learning then there was a Renaissance where people rediscovered the forbidden Greek knowledge which paved the way for The Enlightenment which was the source of all good and freed science from the oppressive clutches of Religion and created modernity and as prosperity and education grows all the world will reject superstition and become secular rationalists and everything will be wonderful.
It doesn't have to be such an obviously false myth as that though. The philosopher John Gray:
Humanists today, who claim to take a wholly secular view of things, scoff at mysticism and religion. But the unique status of humans is hard to defend, and even to understand, when it is cut off from any idea of transcendence. In a strictly naturalistic view – one in which the world is taken on its own terms, without reference to a creator or any spiritual realm – there is no hierarchy of value with humans at the top. There are simply multifarious animals, each with their own needs. Human uniqueness is a myth inherited from religion, which humanists have recycled into science...
When contemporary humanists invoke the idea of progress they are mixing together two different myths: a Socratic myth of reason and a Christian myth of salvation. If the resulting body of ideas is incoherent, that is the source of its appeal. Humanists believe that humanity improves along with the growth of knowledge, but the belief that the increase of knowledge goes with advances in civilization is an act of faith. They see the realization of human potential as the goal of history, when rational inquiry shows history to have no goal. They exalt nature, while insisting that humankind – an accident of nature – can overcome the natural limits that shape the lives of other animals. Plainly absurd, this nonsense gives meaning to the lives of people who believe they have left all myths behind. To expect humanists to give up their myths would be unreasonable. Like cheap music, the myth of progress lifts the spirits as it numbs the brain. The fact that rational humanity shows no sign of ever arriving only makes humanists cling more fervently to the conviction that humankind will someday be redeemed from unreason. Like believers in flying saucers, they interpret the non-event as confirming their faith...
Science is a solvent of illusion, and among the illusions it dissolves are those of humanism. Human knowledge increases, while human irrationality stays the same. Scientific inquiry may be an embodiment of reason, but what such inquiry demonstrates is that humans are not rational animals...
Modern myths are myths of salvation stated in secular terms. What both kinds of myths have in common is that they answer to a need for meaning that cannot be denied. In order to survive, humans have invented science. Pursued consistently, scientific inquiry acts to undermine myth. But life without myth is impossible, so science has become a channel for myths – chief among them, a myth of salvation through science. When truth is at odds with meaning, it is meaning that wins. Why this should be so is a delicate question. Why is meaning so important? Why do humans need a reason to live? Is it because they could not endure life if they did not believe it contained hidden significance?
The silence of animals: On progress and other modern myths
There is nothing wrong with this, we all need a guiding mythos to give purpose to the world and the need for narrative is one of the defining human conditions.
I social/tribal/community meaning is something many folks rely on to feel meaning. But I suggest there are better ways to feel purpose and meaning and that is setting goals capable of the self.
Humans have a need to feel part of something larger than the self. Community meaning is essential.
Right, ideology can be good or bad, rational or irrational, functional or dysfunctional, etc. We assess any given ideology for what it contributes to the whole of a community, state, nation, the planet, etc.
I agree, it is about what it contributes to society. It has nothing to do with how 'Rational' a belief is or some objective truth value though.