soul is literally psyche in ancient greek, so it isn't so much that people try to rationalize souls but that the concept of soul/mind/psyche coincide/overlap from the beginning, now you can go the analytical route and say that it is all just semantic confusion and that we should do hard categories but i think the contrary is better, soul evolved as the mind/psyche specialized to a religious context, recentering it makes it lose its specialness, there is no such thing as the invented (one might say god given) concept of soul; if there is something special to the mind, following this enlarged concept it is (your) uniqueness as tracked by (your) soul (essence)/mind (consciousness)/psyche (yourself as shaped by material conditions)