- Anthony, of Egypt, Saint, approximately 250-355 or 3561
- Anti-clericalism1
- Antiphons (Music)1
- Apocryphal Gospels1
- Apocryphal books (New Testament)1
- Apocryphal books (Old Testament)1
- Apologetics1
- Apparitions1
- Arab countries1
- Argonauts (Greek mythology)1
- Aristotle1
- Artisans--Taxation1
- Asceticism1
- Asceticism--Early church1
- Ashburnham, Bertram Ashburnham, Earl of, 1797-18781
- Astronomy, Ancient1
- Astronomy, Greek1
- Astronomy, Medieval1
- Atlases1
- Augustus, Emperor of Rome, 63 B.C.-14 A.D.1