Whichever theory we adopt to give a rational explanation of human existence, that theory must take into account and explain the mental nature we see at work in all modern communities.
Civilization never stands still; if in one country it is falling back, in another it is changing, evolving, becoming more complicated, bringing fresh experience to body and mind, breeding new desires, and exploiting Nature's cupboard for their satisfaction.
As long as man remains an inquiring animal, there can never be a complete unanimity in our fundamental beliefs. The more diverse our paths, the greater is likely to be the divergence of beliefs.