devout

Short definition from Wiktionary

Adjective

1. 1
   Devoted to religion or to religious feelings and duties; pious; extremely religious; godly.
2. 2
   Expressing devotion or piety.
3. 3
   Warmly devoted; hearty; sincere; earnest.

Noun

1. 1
   A devotee.
2. 2
   A devotional composition, or part of a composition; a devotion.