As I see it, using this definition, an Atheist does require some basic elements of faith, although these elements are in complete contradiction to the axioms that underpin all theistic religions.
These elements of faith are:
1 - The universe operates under immutable and invariant laws
2 - One should believe the simplest explanation that does not contradict evidence (Occam's Razor)
The first axiom underpins the Atheistic knowledge system. The second dictates how Atheistic beliefs are shaped. Most importantly it can be easily demonstrated that all theistic religions reject these two axioms.
"The universe operates under immutable and invariant laws"
Some may recoil from the assertion that this is an article of faith. However the atheist must accept this point on faith alone (ie as an axiom) because science simply cannot PROVE that the laws of the universe are immutable and invariant.
Obviously science has found no evidence to the contrary, and there is no evidence that even hints at the possibility. Regardless, there is no way of definitively proving, say, that the mass of a hydrogen atom won't suddenly change tomorrow.
If atheists COULD prove this, then this would prove that there is no supreme force outside the laws of the universe, which would prove that there is no God.
All monotheistic religions believe that their deity is supreme in the universe, which logically dictates that their deity can alter the laws of the universe at will. (If not, then their deity is no longer supreme.).
The Biblical God is clearly able to alter the laws of the universe at will, as this is the only way that much of the Bible's narrative can be understood.
For example in the flood story, one of the huge scientific problems is with the volume of water that would be needed to cover the Earth. One plausible estimate puts the volume at 300% of the current global water supply. A rational question thus becomes: where did this water come from and where did it go afterwards? Also if it was fresh water, how did the salt water marine life survive? (Or vice versa)
If you accept that the laws of the Universe do not apply to God (ie. the laws are NOT immutable), then the simplest and best explanation is that God materialized all the water he needed to cover the Earth to a depth of six miles, and then simply made it all vanish when it was no longer needed.
He could then just materialise fresh and salt water where needed, and keep the two from mixing (not being subject to osmosis). Alternatively he could have just let all of the sea-life die during the flood and divinely restocked it afterwards.
Even as an atheist, I find this "100% divine" explanation to be far more plausible than the alternative - "God somehow accomplished the flood without breaking the laws of physics".
The laws of physics dictate that some form of positive evidence would be left behind, and that rational explanations can be provided for all of the evidence which directly contradicts it. Even if I accept that the flood pushed up mountains like the Himalayas (see this Young Earth Creationist argument) I still don't understand why those (heavier than water) seashells that have been found at the summit didn't just sink to the lowest point as the waters receded.
So to be an Athiest means accepting that the universe is constant, that its laws are unchanging and no supernatural being can alter them at will. As it is impossible to prove this, it is accepted as an axiom, ie. as a matter of faith.
OK that's it for now. My next blog will examine Occam's razor. If you think I've missed an axiom, let me know.