The following partial definitions of atheism and materialism are taken from the American Atheists web pages:
Atheism may be defined as the mental attitude which unreservedly accepts the supremacy of reason and aims at establishing a life-style and ethical outlook verifiable by experience and scientific method, independent of all arbitrary assumptions of authority and creeds.
Materialism declares that the cosmos is devoid of immanent conscious purpose…
I think the partial definition of materialism quoted is a denial of the very means by which the author has constructed the definition. That, I think, is the fundamental problem of atheist materialism – it fails to account for the inherent purposiveness and creativeness that its proponents quite deliberately employ in order to formulate and express the principles of their own “mental attitude”.
We know, from even casual observation, that, “the whole” is often, if not always, “greater than the sum of its parts” – that is holistic emergence. It happens, so obviously as to be almost unremarkable, at every level of reality we have yet observed. A trio of lonely quarks choreograph their dance to form the original ménage-a-trois, in the process creating a new, emergent level of reality with properties that are unpredictable from the observation of quarks in isolation (if that were even possible). The three become one – a proton, and they are quickly joined by a fourth quark, an electron, who never quite makes it into the inner love triangle but is content to waltz around the periphery giving rise to another novel emergence – a hydrogen atom.
Two of these join together with another more complex atom, oxygen, to form a water molecule and billions of these cooperate to give rise to yet another emergent property not implicit in the underlying level – liquidity. Is the propensity for water (and other molecules) to form liquids under certain conditions an immanent property of the underlying, more fundamental reality, or is it an emergent property that arises from the complexity of the ratios and relationships between the component “particles”?
We could trace the course of emergence onward and upward through the various levels of reality from atoms and molecules, via cells and organs, to organisms, communities and biospheres. At each higher level, higher level functions and properties emerge that correspond approximately to information (data), communication, signal-processing and eventually consciousness and mind. And we must then ask the same question – is the propensity for complex organisms to develop consciousness and mind an inherent, immanent property of the underlying levels of reality, or does it emerge from the complexity of the system?
But at this level, the question takes on a more significant import. If we say consciousness and mind are inherent and implicit in the sub-structure of the universe that gave rise to them, we are subscribing to a kind of panpsychism. If we say it is emergent from the complexity of the system, then why stop there? Why insist that the universe that gave birth to human intelligence is in its entirety nothing more than the simple sum of the nuts and bolts it is made of when there is abundant evidence to prove that almost everything that it is made of is so much more than the sum of the component parts?
We could argue forever about terminology – about whether or not it is appropriate to use the word “God” to describe either the fundamentally panpsychical reality or the “more than the sum of its parts” emergent holistic nature of the whole universe – but in a universe that has apparently, to take a strictly atheist/materialist viewpoint, randomly given rise to the emergence of life and mind, who could realistically deny the possibility of God?