From a recent article in The Guardian:
Peter Singer was in Oxford last week. The bestselling advocate of utilitarianism was the star contributor to a conference in which he talked with a group of Christian ethicists. Given Singer’s inflammatory views on matters such as euthanasia and infanticide, the dialogue was striking for its agreements, particularly the common cause that can be made between Christians and utilitarians when tackling global poverty, animal exploitation and climate change.
However, it was on the last issue that the conference demonstrated real philosophical interest too. Singer admitted that his brand of utilitarianism – preference utilitarianism – struggles to get to grips with the vastness of the problem of climate change. Further, there is an element that comes naturally to Christian ethics which his ethics might need in order to do so. It has to do with whether there are moral imperatives that can be held as objectively true.
I am convinced that the postulation and existence of an omni-type deity of the Abrahamic sort who expresses moral imperatives is insufficient for making moral imperatives objectively true.