What IS good, and how do we determine it?

[Fidel_Castronaut]

Which is fair enough, but surely you can also see the merit to an argument which suggests there is no objective morality, and that morality, like existence, is fluid and subject to change. The parts of our morality which we deem to be unmoving (murder as an example) have just if not more underpinning through an evolutionary argument than they do a theological one. And even then it is not strictly adhered to. Contexts can make that immovable constant a lot more moveable.

The town where I live in England existed over 1500 years ago. The morality of the people there was almost certainly different to the morality which exists in the town today. How does one reconcile this with an immovable, objective moral framework?