devout

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Devoted to a religion or to the fulfillment of religious obligations.
• adjective Characterized by religious devotion or piety.
• adjective Fervently believing in or advocating an ideology or position:
• adjective Fervent or earnest.

from The Century Dictionary.

• Yielding a solemn and reverential devotion to God in religious exercises, particularly in prayer; devoted to the worship and service of God; pious; religious; consecrated in spirit.
• Expressing devotion or piety.
• Sincere; solemn; earnest: as, you have my devout wishes for your safety.
• noun A devotee.
• noun A devotional composition.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Devoted to religion or to religious feelings and duties; absorbed in religious exercises; given to devotion; pious; reverent; religious.
• adjective Expressing devotion or piety
• adjective Warmly devoted; hearty; sincere; earnest.
• adjective devoutly religious persons, those who are sincerely pious.
• noun obsolete A devotee.
• noun obsolete A devotional composition, or part of a composition; devotion.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Devoted to religion or to religious feelings and duties; absorbed in religious exercises; given to devotion; pious; reverent; religious.
• adjective archaic Expressing devotion or piety; as, eyes devout; sighs devout; a devout posture.
• adjective Warmly devoted; hearty; sincere; earnest; as, devout wishes for one's welfare.
• noun obsolete A devotee.
• noun obsolete A devotional composition, or part of a composition; devotion.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective deeply religious
• adjective earnest