Citation needed, massively!
If anything, the powerful technology and knowledge we now wield (weapons of mass destruction, mass surveillance, modern logistics and coordination, global communications) only makes it more important that we don't forget the hard-earned scoial and moral lessons of our pre-scientific ancestors - lessons that were often encoded in evolving cultural systems like religion.
A lot of the more specific day-to-day life advice in those texts are outdated because they're based on societal circumstances of the time, which have changed by now. Or they are explanations of phenomena that we have a much better grasp on now. Or they make claims that are implausible given today's understanding.
Religions teach us some valuable high-level concepts, like love and compassion. Those values are extremely important, but also not terribly interesting. You can totally arrive at them through other means.
I don't see how those high-level values help at solving modern crises of global scale. Believers searching for specific advise on modern day problems need to work hard and read though a lot of "code" to find a few nuggets - ultimately failing to get specific enough answers.
If I do a web search on what the bible says to homosexuality, for instance, I get walls of text discussing precious few bible verses. In effect the bible, being what it is, allows those in charge to impose their individual preferences and opinions on their believers by means of laying out suitable interpretations of the code.
I am tempted to conclude that there is less collected wisdom in the bible than you might think, and more potential for harm than you like to admit.
Nobody was making the argument that extremely specific religious quirks like this are encode knowledge important to the wise use of modern technology.
It doesn't make the discourse more interesting or enlightening, and frankly doesn't belong on this site.
The other context is as a tribal marker, for practical purposes. In this context, the “religiousness” is not about agreeing with the set of assumptions, but pretending to agree and/or going through the motions of various customs as a signal of how committed they are to the tribe.
In societies where individuals need to rely less on the tribe, it might be posited that there is less reason for people to put on a show for the latter reason, so they can afford to be less “religious”. So if, on average, children of Christians are more likely to be economically independent, then they may tend to being less religious, and children of Muslims, who are more likely to be economically dependent on each other, tend to be more religious.
Of course it's not everything, but I don't think humanism on its own would work without an older religion as its "bootstrap".
I feel like if you squint a little you can see all the positive-memetic adaptations that get bolted on to organised religion.
A commandment to “worship no other god but me” is a classic example of something that seems less like profound revelation and more like an effective memetic adaptation.
UsefulChart's video on humanism may help. https://www.youtube.com/watch?v=UWhz3SXPWkg
Absolutely not, because the fitness, in an evolutionary sense, of those memes does not correlate with their truthfulness but with how easy they are to believe because they appeal to our fears, hopes and dreams.
Take that "life after death" trope. The hard truth is that there isn't any, when you die, everything that made up "you" will be gone for good. But no religion based on that truth would ever thrive because the thought is just too scary and bleak.
If he isn't, then he's a powerful (yet imaginary) social construct that has evolved over the past 4,000 years to encode the wisdom of many past generations through a set of rules and stories that happen to match up with the stories and rules of many other cultures. It's also an incredibly fast and low-cost way to reach a solution.
Either way, there's definitely some validity to the claims of any major religion.
The Atlantic slave trade started in the 1500s and ended in the 1800s. Even then, it was controversial and faces opposition from certain Church groups (while getting support from others).
Vilification of gays based on Christian religious grounds apparently goes back to the 11th century (based on a quick read of Wikipedia, TBF), and is only starting to come undone now. I don't really have an answer for this, it was unfortunate.