- Oh Yes! I Can
- Oh, du heiliger Bimbam
- Old Enough to Know - updated edition
- Omul evanghelic. O explorare a comunitatilor protestante romanesti
- On the 28Th Day, My Eyes Opened
- Once upon a Time ...
- Once Upon a Time in a Universe
- Once Upon Unmeasured Time
- One God, One Plan, One Life
- One Life
- One-Liner Wisdom for Today's Girls
- One-Liner Wisdom for Today's Guys
- One-Minute Prayers for Boys
- One-Minute Prayers for Girls
- One-Minute Prayers for Graduates
- One-Minute Prayers for Young Men
- One-Minute Prayers® for Young Women
- Online Dating: Master The Art of Internet Dating: Create The Best Profile, Choose The Right Pictures...
- Online with God
- Opération Jehanne d'Arc
- Orar con la Lectio divina
- Origen on Prayer
- Orthodoxy
- Ostern – Gestern, heute und in Ewigkeit!
- Outdated
- Over The Edge Youth Devotional