A Temple is a building able to be built from the Prehistoric Age. It is used to train Priests and Prophets and also to research bonuses for them. As well as this, any unit within range is safe from Calamities.
Raise Prophet HP. Mysticism, Prophecy and Occultism. (All 90)
Raise Prophet speed: Sandals, Oracle and Tarot. (All 1)
Increase Prophet range: Shamanism, Sainthood and Astrology. (All 1)
Increase Temple range: Ancestor Worship, Monotheism, Crusades and Sunday School. (All 1)
Raise Priest HP: Ceremonial Burial, Inquisition (Both 100), Religious Tolerance and Religious Resurgence. (Both 70). Also Art of Conquest provides Faith Healing which raises it by 70 also.
Raise Priest speed: Mythology, Indulgences, Radio Services and Virtual Services. (All 1)
Increase Priest range: Polytheism, Excommunication, Reformation and Televangelism. (All 1)
Provide additional bonuses: Printing Press (Priests can convert other Priests), Missionaries (Priests can convert Buildings) and Mind Control (20% Priest recharge rate). Art of Conquest also introduces Quantum Theology (20% Prophet recharge rate).