It is helpful to distinguish between absolute morality, objective morality and subjective morality.
As far as I could tell, you only defined objective morality. You said later,
There are moral facts about the world. There are right ways and wrong ways to behave if our concern is to maximise well-being. This is "objective morality".
That definition is a bit ambiguous. Is the definition just the first sentence? Only the second? Both? The second has two propositions, so is it the conjunction of the two? Could you please clarify this and clearly define the other two terms, absolute and subjective morality? Just for clarity sake, so no one is accused of straw-manning.
when we try to apply that bald assertion in the real world it is found to be useless at best.
Do you think that there is a difference between meta-ethics and applied ethics? If not, why not? If so, then why conflate the two? Meta-ethics seems to be the apologists goal here, and so should be of no surprise when it doesn't provide practical content. Further, even if it were useless, would it follow that it is therefore false? Does a propositions impracticality entail it's falsehood?
If the created world is assumed to be a reflection of the goodness of god then we are forced to face up to the carnage
And do you think that in the theist worldview, God's creation reflects that goodness perfectly, or do you think that evil has infested the world accounts for at least some of that carnage? If so, then there may not be any inconsistency.
mass extinctions have violently wiped out more than 90% of living things - difficult to reconcile with Jesus' promise that god cares for every sparrow.First, there seems to be a conflation on whom you are addressing. At the beginning of the OP you say,
One of the most persistent arguments for belief in god centres on the necessity of an ultimate law-giver and epitome of goodness.
But surely you can believe in God without being a Christian, correct? So, to properly focus on the audience and whom you are addressing, I would like to know, are you talking to theists in general or Christians in particular? This may affect some of my future comments.
Second, why think that in a Christian world view, God taking life that he created is the same as not caring for that life?
If the conscience is a result of god's nature in humans
To be sure that you yourself are not strawmanning this, can you cite a theist ethicist who makes the claim that conscience is a result of God's nature in humans? I find this suspect, especially considering the many theists I personally know would vigorously deny this.
then it is a very blunt tool.And? Does that make it false? Nor does it warrant skepticism. Approximation within other sciences, like history, psychology, or even physics, doesn't warrant skepticism, so why here? It's okay to deal in inexactitudes, so long as we work, or philosophize, to minimize them.
The reality is that theists cherry-pick ethical statements from the bible and use then to justify their moral positions post hoc.
Even if true, this just seems to be ad hom, as your thesis is,
show that a supreme being is not required for objective morality.
I dunno man, how badly do you want to discuss these propositions if you have these attacks on people? Kinda makes one unenthusiastic about entering a conversation. Just saying.
We could safely dispose of the words ethics and morality in these sort of conversations without losing anything useful.
Can we hold you to that? Can you, from here on out, delete those words from your vocabulary? If not, I suggest you retract the statement.
It all amounts to nothing more than the what we call our concerns about the way our actions affect the well-being of conscious creatures.
I'd say that's a necessary, but not alone sufficient condition.
challenge for theists is to name an example that does not fit that description
Here you go. Animals have consciousness, but have no moral status.