Scott g asked me why I lose calm when discussing matters related to atheism, which I've been pondering. At root I don't agree that it isn't about praxis, although I accept that the link is not direct.
I think there are two sorts of atheist criticism, and one of them riles me, the other doesn't at all (in fact I find it rather congenial - oops, there might be more on that another time).
The first sort I associate with Dawkins and his ilk, and it is by far the most common sort that I encounter (admittedly this might be triggered by people discovering who I am and what I do). This tends towards supercilious condescension (The God Delusion etc) and is convinced of its own intellectual superiority. This riles me because for various reasons I see it as not only intellectually inadequate but manifestly inadequate; that is, any fair minded investigation of the debate would undoubtedly consider the Dawkins critique to be not just false but foolish too (think of Terry Eagleton's famous evisceration of that book). In other words, what engages me here is a conviction that the truth matters - and these sorts of atheists seem not to care about truth.
Now the second sort of atheist is rather different to this - and in fact, the variety of this second sort is much greater and more interesting than the uniformity of the first sort. Perhaps a better label would be 'non-Christian' rather than atheist, because I would include people with all sorts of diverse understandings here, eg Buddhists, pragmatists, MoQists and so on. Such people can criticise Christian understandings much more radically than the Dawkins-style fulminations because they are a) more educated and understanding of mainstream Christian thought, and b) they accept the reality and necessity for rejecting science as the primary boundary marker for knowledge and wisdom. In other words this second sort of 'atheist' is living in the same world that I'm living in, and we can have all sorts of productive conversations - and we do.
Really what my "thresholds" were about were fencing off the first sorts of atheists; or, perhaps a bit more defensible, they are ways for me to work out what sort of atheist I am engaging with. I really enjoy and value the conversations I have with the second sort, but not the first, which I find frustrating. Now that is a spiritual issue, because I don't think that this reaction of frustration and anger is a defensible one; it's a fault in me. Hence I need to try and cultivate my inner calm.