Of the first set of postulates, two of them are false, P1 and P3. All morality is subjective, as it relates to one's relationship to others, who have a different viewpoint. Deities cannot be used as a source of morality, as they don't exist and people have different ones with different beliefs.

I would definitely need an example of what a "moral truth" is because I honestly can't think of anything I value as a moral that would always true in all cases. I mean even an objective morality today would likely change tomorrow if aliens landed on our planet or the moon.

I would rather pursue the idea/discussion there is no such thing as objective morality because the only basis for moral objectivity is what defines theist. They are the only ones in my perspective that can have any objective morality and in practice we know that is definitely false. Even the "objective" morality changes so it too is actually subjective or relative. I mean catholic morality is different than prodestant morality and they are "based" off identical text. Let's not get started on "thou shalt not kill" or "love thy neighbor"

Morality should change with growth and education and all sorts of external factors. I mean technically that is part of why we (humans) lay claim to be the "superior" species on the planet

It's useless discussing this with theists. is the political organization of theism. grew to enforce the moral behavior of the people. It's a lot easier to get people to behave when there are bonuses and consequences that never have to come true. You see the same kind of blind belief in the US, when it comes to the constitution and the interpretations that are manipulated to fit beliefs. Or the knee jerk reaction when the word socialized is used. It's programmed belief that is reacted to. Just the same as programmed theism.
Ideologies or pragmatism are the opposites. Theism is just one of the ideologies.

I've had the ridiculous debate with a theist. He insisted it was impossible for him to be moral without his god. I said that I won't turn my back on him, because trusting him would be foolish of me. You never know when he might lose his belief. He will become dangerous to be around .

It's useless discussing this with theists. is the political organization of theism. grew to enforce the moral behavior of the people. It's a lot easier to get people to behave when there are bonuses and consequences that never have to come true. You see the same kind of blind belief in the US, when it comes to the constitution and the interpretations that are manipulated to fit beliefs.
Ideologies or pragmatism are the opposites. Theism is just one of the ideologies.

I’m guessing ‘objective’ means universally, permanently true. So that would rule out our individual, time-bound moral value systems. So objective values would be, in a sense, above the individual. In a hierarchy of value systems, objective values would be at the top. That’s probably where God came in. I think this is because there was no concept of aspiration apart from God. Man either aspired to be a god or to be God-like. Nowadays we’re trying to separate the two ideas.

Seems to me that there are secular Buddhists, agnostic Unitarians, atheist physicians, humanists, and others who adhere to an oath or principal successfully enough to be good people.

would it occur to them to even ostensibly show the necessity of theism for adherence to rules of polite society? I dunno.

I seriously do not have a clue what you are talking about, as far as I am concerned all we need to know is that some people are good and some are not, do we need to go any further?

I like your reasoning and agree with your conclusion. I'm more of a constructivist than a realist though and I think we can find essential first principles that are objective though not necessarily made true in virtue of empirical science although science would likely find these to be common amongst successful societies. In observation we might be able to conclude through rationality that successful societies share common characteristics (e.g. social cooperation and cohesion, consistent application of the law, fair and equal access partake in constitutional government, a system of labour that enables prosperity and incentivizes bringing goods into the pool of shared resources, the ability to defend itself from hostile neighbours) that are necessary for survival (i.e. if the society didn't have these things, the society would fail to operate, at least in the long term). We might know these rationally because they follow from the first principles provide the definition of what we would a successful society. It's to describe exactly what the laws of this kind of society would be or the kind of system of distributive justice it might enact because history and anthropology has shown us many different civilizations that have come to fruitation which have followed different laws and have agreed on different means of socio-economic redistribution. However because the particularities are different, it doesn't follow that we are unable to find any commonalities between societies that have been successful and others that have not.

It's a bait and switch.

Modern religious people say religions contain good moral principles, like thou shalt not murder. It's implied that they are good because of common sense. But then they say that there is no way to know they are good without accepting them as blind dogma, which is incompatible with common sense.

An easy way to remember it is that, from a dogmatic standard, all the crazy stuff like a virgin birth, jihad, etc is as equally valid as thou shalt not kill. There's no discrimination between crazy and common sense.

Even if a commandment is thou shalt not kill, faith, when used as an underlying basis, undermines common sense standards like thou shalt not murder That's because faith regards morality as obedience to a will that can change its mind and thereby change the laws of morality at any moment (think Isaac and Abraham), not common sense, objective standards. If God changes his mind and wants you to murder Isaac, thou shalt not murder is now though shalt murder.

Religion is subjective morality.

I don't follow the logic, but maybe I misunderstand the symbolism. It looks to me like you are giving three premises, viz., P1, P2, & P3, and from these three premises I understand how theists draw the conclusion, viz. C=Therefore God exists. But I don't see that you go there; instead, it seems to me that you say "If P2 & P3 then P1," and I don't see the sense of this. First, you already have P1 as a premise; and second, I see no reason to accept what (I think) it symbolizes as true. That is, I just don't believe the following conditional statement: "If (P2)anything objective must have a basis and if (P3)only a deity can be the basis of morality, then (P1)objective morality exists." But maybe I have misunderstood....

Whether objective or subjective, I lean toward moral relativism—that our actions should be freely adaptable to circumstances. If society or instinct prescribes a correct behavior pattern then it is objective. If a person figures it out on his own, then it is subjective. The goal of behavior either way is well-being and survival, with balance between individuals and the group in mind.

IMO, morality is a rather shallow concept. A moral person is one of whose actions we approve. An immoral person is one who doesn’t please us. Maybe it would be better to speak of behavior rather than morality. Immorality is a sin against God in some circles, while misbehavior is is just making mistakes. God does not judge our behavior—we judge our own behavior and make adjustments as needed. We are extensions of God IMO.

If you don’t like what somebody’s doing, it seems more logical to try and understand why they are doing that thing rather than to judge them to be immoral.

Of course if they are a threat you might have a duty to take action against them, but that is not moral judgement.

I actually got into an argument with a history prof in college regarding morals. He asserted that morals were a static thing, unchanged throughout history... I responded that morals had clearly undergone massive changes in the last 2 thousand years... I asked him how it was morally responsible to keep slaves in the past when it clearly isn't now... He said it never was... I stated that according to the moral "guidance" for thousands of years it was... he didn't like me too much after that... I simply stated that morals are dictated by the society in which they're "authored" and not by any static set of tenets.

Humans are social animals, morality is the term we use to identify the instincts that make us more acceptable to the humans around us. Morality is not objective, but it is only subjective based upon mass opinion due to the need of the individual to interact with the group.

It's not a mystery and it's certainly has nothing to do with religion although they claimed it and routinely fuck with it.

The book is full of morality you murder a woman for not being a virgin, you wipe entire towns because your imaginary god tells you too! Then the morals of murdering someone for working on the sabath. Then the morals of murdering your unruly kids, selling them into slavery beating your slaves is ok as long as you don't kill them.

Hey, my relatives are good people!

Theists are tricked into thinking it forms consensus morality because of how widely it is shared.

Because it is imposed, theist morality is inferior.