"If one is a Calvinist, one might say that God gives the "brain chemicals" necessary for belief to his elect. And many classical Christians, who are not Calivinists, view belief to be an act of God on man (regeneration) rather than a voluntary act of man, himself."
As a 'Calvinist', I would not say that. I may say that God, from all eternity foreknew the 'brain chemicals' I would have at any point during my life. And, that I would not have the "God Gene" when I was (physically) born; and He would, as an act of mercy and grace alter my brain chemical make-up so that I would believe and accept his offer of salvation. That point of changing my brain chemical make-up could be called "regeneration".
For the record, let me make it clear that I believe that the "God Gene" construct is total nonsense.
Religion and science have been clashing for centuries and both have somehow managed to thrive.