Civ Religions

We talk a lot about civ geography here, but given the existence of monks in the game, I think it is relevant to talk about what religion(s) each civ historically followed.

Here's what I think, feel free to correct if necessary.

Britons: Catholicism --> Anglican

Byzantines: Eastern Orthodox?

Celts: No clue

Chinese: Buddhism

Franks: Catholicism

Goths: Atheism

Japanese: Buddhism

Mongols: Buddhism?

Persians: Islam?

Saracens: Islam

Teutons: Catholicism

Turks: Islam

Vikings: Atheism?

Aztecs: Tribal?

Huns: Atheism

Koreans: Buddhism?

Mayans: Tribal?

Spanish: Catholicism

Incas: Tribal?

Indians: Hinduism?

Italians: Catholicism

Magyars: No clue

Slavs: Eastern Orthodox

Berbers: Islam?

Ethiopians: Tribal?

Malians: Tribal?

Portuguese: Catholicism

Khmer: Buddhism?

Burmese: Buddhism?

Malay: Buddhism?

Vietnamese: Buddhism?

The civs I am most confused about are Magyars and Celts, but there are still a lot of uncertainties. Let's discuss.