Why do atheists deny that they are just biorobots?

[Chas]

Belief in God counters ontological naturalism by providing a basis for formal and final causes. Without these two supplements to efficient and material causes certain features of reality, like the persistence of sensible bodies throughout change, are left unexplained.

You are stuck on 2300 year-old philosophy. I, for one, don't accept Aristotle's definitions as valid or meaningful, so I find your argument tired and tattered.