One of the topics debated was that of morality.
Most arguments or debates on morality between christians and atheists come down to the question of where morality comes from.
In the debate, the christians claim was that god is the source of objective morality and that such morality is communicated through the bible.
The idea of an objective morality is hard to support, because each human is (by definition) their own subject, and any objective morality interpreted by a subjective human must result in a subjective application.
Objective + Subjective = Subjective
This is not to say that the result of an objective moral judgment and subjective moral judgement must necessarily be different. However the deistic purity of the objective morality claimed by christians is subject to subjective distortion via the many and varied humans performing the interpretation.
The atheists claim in the debate was that morality is innate, either as a result of evolutionary imperatives or from an intellectual basis (such as enlightened self interest).
(please excuse my gross simplification of the arguments for the purposes of this post)
I'm going to avoid a deep discussion of the sources for human morality for another (much longer) post.
What neither side seemed to raise in the debates, was the limitations of the bible as a tool for determining morality. Specifically that the bible is a finite state machine.
By finite state machine, I mean that there are a limited number of parables, morality plays and direct behavioural edicts in the bible, all of which were written between 1.8 and 3.5 thousand years ago.
So it would be reasonable (read necessary) to expect that not every possible modern question of morality is dealt with in those pages.
Therefore in such situations where a clear and definitive moral ruling is not supplied, or where multiple conflicting moral laws seem to apply, christians must use their best judgment to determine how to interpret the bible.
Best judgement using their intellect and innate morality, any such interpretation made by a christian must eventually rely on those faculties.
Thus the arbiter of any moral ambiguity in the bible for a christian is same as the starting morality for an atheist.
I'm not saying that there is no morality in the bible - I think the bible contains great morality as well as great immorality. What I am saying is that human morality is useful without the bible but the bible is not useful without human morality. The same can be said of any finite text claiming to be the laws of god. In the end all moral decisions are human ones.