I think it would be religion to not believe that it is theoretically possible to build a device which emulates the human brain - sort of like the belief that it

I think it would be religion to not believe that it is theoretically possible to build a device which emulates the human brain - sort of like the belief that it was impossible to make 'organic' compounds out of compounds from 'inorganic' origin because they lack the vital force. Whether it will ever be possible to do it on a physically possible Turing machine in real time is perhaps slightly more debatable.