
Theists can appear superficially successful in such debates, especially if they happen to be ordained priests used to preaching to a congregation. When it comes to public speaking, practice, I imagine, can be an advantage. Comment about the debate appeared on the associated blog, including from Ian Powell, the debating theist. His comment revealed the basic disagreement that I'm attempting to address:
...I really am genuinely puzzled that quite a few atheists don’t seem to see the logical rational difficulty (at least) of starting from base reality of energy etc and working step by careful step to an intellectually coherent binding moral "ought" – socially convenient ought- yes , evolutionary helpful ought - yes – but not one that has any ultimate legitimacy.
This misses the point. Christians who ask "Where is your ultimate authority?" frame the question on the basis of their own ultimate authority, namely God, or the Bible as the word of God. If an atheist claims neither of these as the ultimate authority, the theist naturally wants to know what actually is the atheist's ultimate authority.
But there is no ultimate authority. Not God, not scripture, not the Ten Commandments, not the Humanist Manifesto. Nothing. The ultimate authority does not exist. Morality has evolved as a way for humans to survive in social groups, and continues to do so. Now that social groups can be global, morality needs to reflect the aims and wishes of worldwide communities. Rigidly clinging to ancient dogma is, at the very least, inappropriate.