This term does not exist in Wikipedia yet although it is not unknown to the internet community. You may want to google the terms biotheism/biotheist, and some entries pop up. Not serious staff actually. Some people call themselves biotheists in forums, even a facebook entry exists, and amazon lists a book that is not available anywhere.
Maybe some biotheists understand their religion a naturalistic one, maybe based on Spinoza’s tenets. I’m rather inclined to dismiss any religious zeal even if connected with naturalism. The most recent offspring of such irrationalism based on some science is probably Darwintheism. It includes people becoming furious when someone mentions that there is some progress to evolution – true Darwintheists as all theists deny progress – and to evolutionary theory in particular.