Synonyms for Devout (same or very similar meaning)
WordNet sense 1 (earnest):
dear, earnest, heartfeltWordNet sense 2 (open and genuine; not deceitful):
sincereWordNet sense 3 (devoutly religious):
god-fearing, piousWordNet sense 4 (having or showing belief in and reverence for a deity):
religiousFrom the ODE community, based on WordNetadd/edit