In the west, as the ideological war between science and religion grew, Descartes proposed the truce of dualism based on “I think, therefore I am”. Why not have mind and body, the spirituality of religion and the physicality of science? This divided scientists into atheists who believed only in the physical world, theists who believed in a world beyond it as well, and agnostics who couldn’t decide. This marriage of convenience worked for a while but it didn’t last, as now science in general denies the spiritual.
The problem for dualism is how can two distinct realities interact? If mind and body don’t interact they aren’t relevant to each other. What use is a mind that can’t affect the body? Or if they do interact which came first? A mind that emerges from a physical brain is like a superfluous gas given off by a physical heap, while if a non-physical mind creates the world, why is it such a mess? Either way, if one is real then the other isn’t, or at best it is irrelevant. And if the two realities are in conflict, why hasn’t heaven purged earth already or earth corrupted heaven? If mind and body are sides of the same coin, what is the coin?
Facing such challenges, dualism is currently in retreat before the monism that there is only one reality and it is physical. Monism is simpler than dualism, so when scientists say the physical world they study right now is real and theologians say a future spiritual world is real, many people prefer now to later.