On theism, why do humans have moral duties even if there are objective moral values?

[Mister Agenda]

Virtue is its own reward, as they say.

[BrianSoddingBoru4]

I was listening to William Lane Craig's moral argument. Even if we grant him that God exists and objective morality exists and god is the basis of objective morality, why do humans have moral duties? Why do we have to be good and do good other than for a selfish interest in going to heaven? He just claims that we do have moral duties (just like he claims by fiat that objective moral values exist). But why, on theism, do humans have a moral duty to be good?

I don't know what William Lane Craig says. He gets a lot of attention these days, but I don't find him to be a very interesting thinker.

There's a lot of variation among Christians, of course. So you'd get a variety of different answers if you went to a Christian site. I can outline the view that I studied, when I was reading Christian theology:

~ Human beings are a certain kind of animal, with particular needs, abilities, limitations, etc. 

~ There are ways of behaving that are suitable to our particular qualities, and ways that aren't. The best behavior is that which aims toward our best overall well-being. 

~ We may not understand what is best for us in any given situation. This is why we have various institutions to provide guidelines. (Though of course institutions may fail to know well.) 

~ Humans are by nature social animals. No one is an island. One's overall well-being depends very much on the well-being of others. 

Morality and ethics are the norms we use to aim toward what is best for us, which includes what is best for everyone else. 

"Moral duty" means the recognition that it is bad to harm ourselves or others, and the commitment not to do so. It means adopting the responsibility of behaving with the well-being of ourselves and others constantly in mind.

This is a very humanistic approach to the value of moral obligation, and one with which I heartily concur.

However, it doesn’t come close to addressing the OP’s question, which is ‘Why, on theism, do humans have a moral duty to be good?’. (Bold mine)

I think the only coherent answer to that question is, ‘Because God said so.’ If, as the majority of Christians believe, God is both the foundation and arbiter of what is moral, then God is unable to not issue moral dicta, include the one instructing humans to behave morally.

That being said, I much prefer your humanistic approach to moral behaviour to a divinely imagined one.

Boru

[The Grand Nudger]

IMHO references to objectivity often entail the notion that attaining a third-person perspective, i.e. a God's-Eye-View is conceivable. But if it is truly concievable, as opposed to say just imagined, then the object of that conception would be God. So really objectivity entails the concept of God in at least as much as it is possible to percieve the universe from the outside.

Few minor issues here, if we're speaking objectively.  A third person perspective is not extra-universal.  A third person perspective is not a god's eye view...or even close to it.  A third person perspective is not a requirement for objectivity.  

Do you think it might be consequential to a persons conclusions if they manage to get every assertion wrong?  Handily, this does double duty in answering the OPQ. 

@Pnerd
We insist that we have moral duties, regardless of whether any gods exist, because we understand that actions of moral import have consequences. We must be good, because if we weren't that would be bad. Duty (of any kind) is a strongly consequentialist notion - the foundations of deontology being laid in the known or imagined or perceived outcomes between disparate acts.

It's my duty to feed my children, for example..because they can't feed themselves. Because, were I not to feed them, they would starve, and starving people is bad. That's before you get to the elective nature of most duties. Not elective in that if you have a duty you can decide whether to do it - that's ruled out in the definition of a duty. In that we largely choose what we're duty bound by. To starve a person is bad. To create a person to starve..worse. Duty and deontology have been incredibly useful to institutions - read my sig for an example - so..while it may be that we don't have duties, things we must do, objectively...it's easy to see why we might assert as much anyway. In the end, there isn;t anything stopping people from engaging in an elective objective morality. You can clearly see what's right and what's wrong as a point of fact - but..even if so.. that's not the end of the story, only the beginning. We may see right clearly, and elect not to satisfy it. We may see a thing for the wrong it is, and wholeheartedly engage in it anyway. Picking and choosing when we're moral.

[The Grand Nudger]

Virtue is its own reward, as they say.

Often enough, a very expensive reward, lol.  That might play into the above - why we strategically fail in our duties. A minimally moral agent has no duties or as few duties as possible - and this makes moral success alot easier to manage.

[Pnerd]

However, it doesn’t come close to addressing the OP’s question, which is ‘Why, on theism, do humans have a moral duty to be good?’. (Bold mine)

Thank you for pointing that out. Many of the answers here haven't answered my question, which was "Why, on theism, do humans have a moral duty to do good or be good other than for a selfish interest in going to heaven or avoiding hell?". Most replies here answered some other question.

[The Grand Nudger]

For the same reasons as we would under any other view. Just as we would not possess such a thing, for all of the same reasons…in either case.

The question of whether a god exists is irrelevant to moral objectivity.

[Angrboda]

Most replies here answered some other question.

Since that doesn't appear to be true, I have to wonder why you're not seeing them. The primary answers given were a) doing good is rewarding in itself (both natively and because God has made it so [Angrboda, Mister Agenda]), and b) Natural law makes being good rewarding (because God has made us so that doing good is natural and unproblematic [Belacqua]). If I were to guess, you're looking for an answer with specific properties (it fits your preconceived ideas, it answers some previous argument, it satisfies you intellectually, etc.), none of which actually follows from the question you asked.

[brewer]

However, it doesn’t come close to addressing the OP’s question, which is ‘Why, on theism, do humans have a moral duty to be good?’. (Bold mine)

Thank you for pointing that out. Many of the answers here haven't answered my question, which was "Why, on theism, do humans have a moral duty to do good or be good other than for a selfish interest in going to heaven or avoiding hell?". Most replies here answered some other question.

I think I answered your question very accurately. Worship god = good, don't worship god = bad, don't worship god but then take it back = good.

When it comes to gods,......... humans make funny rules.

(I noticed that you have not rep'ed me, look out, you might get smited)

[Pnerd]

Thank you for pointing that out. Many of the answers here haven't answered my question, which was "Why, on theism, do humans have a moral duty to do good or be good other than for a selfish interest in going to heaven or avoiding hell?". Most replies here answered some other question.

I think I answered your question very accurately. Worship god = good, don't worship god = bad, don't worship god but then take it back = good.

When it comes to gods,......... humans make funny rules.

(I noticed that you have not rep'ed me, look out, you might get smited)

I'm not asking about worshipping; I'm asking why theists believe they have a moral duty towards other humans (I agree that was not made clear in my question). And secondly, the last part of my question was "other than for a selfish interest in going to heaven or avoiding hell". Your answer seems to be about god's reward and punishment as a motivation for theists to do good. By the way, why is worshipping god = good according to a theist (other than divine reward/punishment)?

[Pnerd]

Most replies here answered some other question.

The primary answers given were a) doing good is rewarding in itself (both natively...

Theism isn't necessary for that. That's why I don't find that a useful reply.  

... and because God has made it so [Angrboda, Mister Agenda])

Do you mean God has made the rules that doing good would result in reward in the afterlife? The last part of my question was "other than for a selfish interest in going to heaven or avoiding hell". "God has made it so" (if it means doing good would result in divine reward) seems to be about god's reward and punishment as a motivation for theists to do good, which is something my question wasn't/isn't looking for in an answer.

... and b) Natural law makes being good rewarding (because God has made us so that doing good is natural and unproblematic [Belacqua]).

I probably missed or misunderstood this answer previously. This one makes sense.

If I were to guess...

Please don't. It's a shocking habit; destructive to the logical faculties. 

... you're looking for an answer with specific properties (it fits your preconceived ideas, it answers some previous argument, it satisfies you intellectually, etc.), none of which actually follows from the question you asked.

You can ask instead of guessing.

It could be that I didn't manage to communicate my question properly (English isn't my first language). 
.