Piety is a word used to describe a deep reverence or devotion towards a religious belief or practice. It refers to the sincere and loyal commitment to one's religious duties and showing respect towards a higher power. Full definition
If one would rightly serve the unseen God, one performs acts of piety in ways that avoid being seen. (religion-online.org)
The history of the personal piety of these religions is largely a history of mysticism of the speculative - theological kind as well as the mysticism which expresses itself in simple prayers. (religion-online.org)