Most materialists do not behave as though the love of their children is a chemical reaction, or killing someone they object to is the inevitable result of a rise in blood pressure, or synapses misfiring. They may believe those things in the abstract, but as they make no difference to how they live their everyday lives, their beliefs and the practice of them is inconsistent.
How is that inconsistent? I see love, morals, emotions, conscience etc. as evolved traits.
They have an obvious function if we consider we are a social species that got an evolutionary advantage of acting in group. We are a species that need a long childhood to absorb all the cultural knowledge we need to survive, so a deep love for our children is necessary to sustain the long effort of bringing them up.
Whether you agree or not, i think we can make a coherent case that all human traits can be explained in a naturalist framework through evolution.
Now I realize you probably disagree with all that, but that does not make my position inconsistent.
I do not understand how trying to explain how a human being works makes one less human, it is not going to override the billions of years of evolution that it took to become the humans we are.
If i believe that on a cosmic scale there is no goal to existence, that does not mean that i cannot have the sense of purpose that is forced upon me by evolution, after all i do not live my life on a cosmic scale.
Explaining that sense of purpose does not magically make it disappear.
The real inconsistency would be quite the opposite.
A materialist explanation for human behaviour demands that we are largely incapable to escape our evolved behaviors and instincts.
The ultimate inconsistency would be to start behaving contrary to that.
We can not place ourselves outside of our humanity, even if we try.