I mean, it's not like religion is evil
I would argue that religions which have moral imperitives are evil. They inherently deny the indifvidual the authority to make their own morality judgements and impose morality judgements that the individual is not permitted to question(Lacking a committment to god's authority is usually an official failure condition) and doesn't understand(They may have an understanding of it of their own, and agree with it independantly, but they are doing it for religious reasons and are not permitted to question those reasons sufficiently to understand them.). Externally-imposed morality imposes responsibility which is fundamentally incompatible with personal responsibility which is required to maintain personal morality.
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A morality that isn't challenged isn't justified...
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It isn't even enough to personally verify religous morality. One needs(In order to justify it) to generate their own morality independantly. It is the old arguing trick of going on the offensive. You can say "The president committed election fraud.". One reply is "There is no way that it is possible. They would have revised the security after those problems with the virus busters going wrong!". Another reply is "You keep crying about healthcare, but when you had your chance, nobody wanted it!". The latter is going to be far more effective because people will be too busy yelling about how wrong you are to remember their original issue. If ou start by verifying that you agree with the morality that you have been given, then you have already lost the chance to find out if there is a better one...
explain (to less... intelligent people who don't get the concept of common good, and think that stealing is good, because it's good for that person)
I would say that it is not so much that less intelligent people don't understand that good for them is the limit of morality. I beileve that far more common is people compatmentalising morality "It is good that I make money. people's lives may or may not get ruined as a result, but that is an unrelated issue.". Another is mindlessness(Which is the default function of the human mind) "Wha? Hurting people? Naaa, we were just having some fun! I mean, sure, there was screaming and crying and bleeding and dying and stuff, but that is just how these things go, y'Know?". Then there is familiarity "Huh? Arbitrarily dictating life or death of entire populations without justification? Brutal regime that inhibits freedom too much for a mentally stable society? Stop being silly! That's just Hitler! Everyone know he is a good guy. Finally someone willing to stand up and stop those scheming jews from stealing our nation out from under us! It is about time we had someone honest and decent to end this ridiculous apathy and fix things for the better..."... It is not so much that people are not intelligent, but that they do not apply their intelligence to their objectives or justifications.
Morality creates religion, as a way to explain and enforce it and probably some other stuff.
Shit's straight up definitionally impossible without it being done to follow God's will. Morality in that case, basically, is not what you do, but who you do it for.
Humanity? As a species, and a "greater" concept?
I have difficulty parsing this, but I believe that you are saying that you can do things for humanity in place of doing things for god. Which sort of seems to be missing the point of the original statement of religion defining good as being god, and thus what humanity believes is irrelevant. I would argue that humanity as a species is a terrible god. They are clearly insane. They think that they are bette than animals because thye can build cities and guns and art... Animals can build settlements and weapons and art. Humans are largely incapable of building complex weapons, sophiticated art, and large settlements. These things are built by humans, but only by relying upon unfathomable generations of human civilisation. Humans have a high talent for language and manipulation of sturdy objects. Baiscally, humans are gifted at making records. I very much doubt that you would see a single generation of humans come up with something as sophisticated as a rock combined with a stick outside of an extreme instance of inspiration. Humans are naturally inclined to think the most of themselves for no reason. It is basically the same as religion, it ends up being all about obediance and lacks justification.
without God there'd be no reason to want anything else and morality would pointless, as everything would be become nothing upon death.
Also your kids.
You kids become pointless unless they also have kids, and those are only as valid as their kids, which are only valid because they have kids, which they might not, and the concept of all possibilities occuring if provided with sufficient time indicates that eventually there will be no kids. Also entropy/gravity-death of the universe, or armageddon... But really, justifying kids with more kids is dependant upon valuing kids, and provides no inherent value for kids itself. You may as well just say that kids are self-evidently reason-for-being and thus everyone is self-evidently meaningful because everyone was kids at some point... Unfortunately some people don't feel that humans, even children, are self-evidently meaningful. Otherwise, would people be asking why their own existence is meaningful?
For myself, I feel that the best available meaning of life is to seek out a good meaning of life. Which has various quite promising implications. I feel that the inherent meaning of life is to "be yourself" in an evolutionary sense. Which is abysmally bad for a whole host of reasons, not least of which is that there is nobody at the helm and that the whole system is composed of lotteries, but the imminent doom is perhaps the most off-putting. Perhaps the most plausible of the vaguely defensible options is to express the self that you can be proud of. This largely involves throwing away human impulse and adopting understanding and prediction, as otherwise you won't have a clear understanding of what you can be proud of and won't be in a position to control what you express.
As for what Christians religions belive was pre-Jesus - God's morality and laws which are also pretty much the same (although with more gay hate) since they're the same thing (for most part), and that all religions and people in general get the moral code from God because he kinda imprinted it in humans when he created them (although the recognition came only after the fruit of Eden thing) so the "voice of God" echoes through everyone and all religions because we deep down know what is true?
As for what was before Jews, then yeah, there was nothing, since, you know, world is apparently 6000 years old (or something around that) according to Bible, so there was always religious code of laws (in a way, although commandments came later, I suppose?).
If a god's morality is inherent, then everyone should know to obey that god without needing to be converted. Devosion to that specific religion should be as common as not murdering. The existence of wide-spread adoption of incompatible religions is good evidence that such is not the case, or that the god in question doesn't actually regard worship as being as important as murder.
As for the 6000 years old thing? There is loads of evidence that such is not true. Enough that I would say that it goes beyond "the gods just like the idea of things being in progress when they started" and well into "the gods are deliberately lying to us". There are just too many details to it, they could have just had everything break down over that span of time and we would have just accepted it, but no, they needed to splat down whole evolutionary trees and weird extinction events... Now, if the gods in question say that lying is okay, then fine, religion of unreliable texts and shameless P.R. campaigns is willing to live up to its own standards. And why not? Everyone loves trickster gods! But a lot of these religions make quite a big deal about their texts not being written as a shameless divine P.R. piece and suggest that lying is bad...
It is though. Archeological evidence and, you know, common sense indicate that the pack instincts and whatnot came a lot before first ritual burials and other stuff that could be considered religion.
Unless bacteria also belive in bacteria Jesus, or something.
I would say that bacteria jesus is unlikely. But bacteria commonality is quite likely. there really isn't that much special about humans. I suspect that the human internal monologue is the highlight, and I doubt that it is completely unique. On the other hand, internal monologue is not necessary. I am pretty sure that I didn't have an internal monologue until after I learned to read. I remember being asked to "read silently" and just had a complete "huh!?!?" moment. And we certainly formulate ideas without spelling them out, so that really isn't a thing. I could easily see bacteria having decision-making functions that focused on the self and decision-making functions that focused upon the group and that the latter could be equated to religion. I can see how people could question if such a thing is a mind, but to me it is just a whole great tower of different methods of determining outcomes, with rocks almost certrainly near the bottom with their "roll down until stable" operation and humans near the top with their "if problems arising from acquiring food is less than value of food + hunger+expecation of food in the future then acquire food" operation.
Really, free will is a false concept. It is not as though it does or doesn't exist, but there is no point to it either way. There is no potential for variation. All decisions are a product of mind and circumstance. mind and circumstance are entirely derived from mind and circumstance all the way back to the start of mind, and the forces that led up to that are a product of immutable processes from origin or infinity. The outcome of random chance is inevitable, regardless of whether it is predictable. The ridiculous cience-fiction notion of a parallel world being created every time a person makes a decision is ludicrous. the closest that could happen is infinite worlds with slight variations that resulted is varying decisions, possibly even commencing at the point of variation. The outcome is the same, but the process is completely different. The important point of all this is that the human mind possesses zero potential for variation from its inevitable course. The rock rolls downhill with the same certainty that the hippy feels that a war for the purposes of increasing the support for the ruling political party is bad. People think themselves far too special. The only power we have is to be party to invoking a specific result, or we can be amongst the rocks who abandon that and go with their impulses. I like to think that people would be party to making a better world if they saw it as a possibility.