Spiritual reading covers topics like God, ultimate truth, love, faith, and happiness.
They are metaphysical concepts which are in the world of infinity.
If the topic is for everyday life, natural languages will be good.
But natural languages are not proper for the infinity world.
This problem can be solved by formal languages which can manage infinities.
This book introduces some mathematical backgrounds to the formal languages and some key concepts in religions.
The Kingdom of God and the Heavenly Kingdom are the same and distinct.
If you cannot distinguish, you do not clearly understand Judaism or Christianity.
Nirvana and Tao are the same and distinct.
If you cannot distinguish, you do not clearly understand Buddhism or Taoism
