I feel like there are two different notions of the word 'objective' at play here. One is the one you use, of whether there is a truth of the matter in moral questions or only 'thinking makes it so'. The other is whether, assuming that the truth of the matter exists, we have faculties that can arrive at said truth in some universally accepted manner. In the latter sense, there seems to be a true difference between mathematics and ethics. While there are long arguments to be had over what it means for a mathematical statement to be true, mathematical platonists and logicists can still happily agree on whether a particular proof is correct or not (I'd think). This is rather different when it comes to morality: for example, contemporary attempts to derive ethics from purely rational grounds are, ehm, not very successful, as Dawkins amply demonstrates.
So, even as a Christian, I find myself agreeing with Holland on two fronts: first, one needs to sort out the metaphysical groundwork first, before having even the possibility of objective moral truth (*if* you start from Humean premises, you'll end up with Humean conclusions). Second, not only are the metaphysical premises logically necessary, they have also proven to be necessary historically. Christ's teaching wasn't just reinforcing something that everyone already knew by the natural light, quite the opposite: it reshaped our moral sensibilities in fundamental ways. And, while the ethical tree can outlive its cultural-metaphysical roots for a while, eventually it withers and then [the history of the XX. century] follows. This is not to say that it is not objective in the sense you define, but it does have a revealed component that is not evident to reason alone - at least not in practice.
(As an aside, I think the case of abortion is a somewhat special, in that one can make a strong argument that *if* murder is wrong then so are abortions, other philosophical issues notwithstanding)
I feel like there are two different notions of the word 'objective' at play here. One is the one you use, of whether there is a truth of the matter in moral questions or only 'thinking makes it so'. The other is whether, assuming that the truth of the matter exists, we have faculties that can arrive at said truth in some universally accepted manner. In the latter sense, there seems to be a true difference between mathematics and ethics. While there are long arguments to be had over what it means for a mathematical statement to be true, mathematical platonists and logicists can still happily agree on whether a particular proof is correct or not (I'd think). This is rather different when it comes to morality: for example, contemporary attempts to derive ethics from purely rational grounds are, ehm, not very successful, as Dawkins amply demonstrates.
So, even as a Christian, I find myself agreeing with Holland on two fronts: first, one needs to sort out the metaphysical groundwork first, before having even the possibility of objective moral truth (*if* you start from Humean premises, you'll end up with Humean conclusions). Second, not only are the metaphysical premises logically necessary, they have also proven to be necessary historically. Christ's teaching wasn't just reinforcing something that everyone already knew by the natural light, quite the opposite: it reshaped our moral sensibilities in fundamental ways. And, while the ethical tree can outlive its cultural-metaphysical roots for a while, eventually it withers and then [the history of the XX. century] follows. This is not to say that it is not objective in the sense you define, but it does have a revealed component that is not evident to reason alone - at least not in practice.
(As an aside, I think the case of abortion is a somewhat special, in that one can make a strong argument that *if* murder is wrong then so are abortions, other philosophical issues notwithstanding)