The labarum was adopted by the followers of Mithras.
Background[]
The symbol was commonly used by Roman soldiers with whom the worship of Mithras was extremely popular. The symbol was eblazoned on many warrior's shields for he was primarily a soldier's god. The symbol was formerly carried upon banners into battle.
A labarum was in the Chapel of the Two Gods in Camelot for those knights who stil worshipped Mithras. When Arthur brought the Grail in the Chapel, the labarum miraculously disappeared, marking the dominance of Jesus Christ in the kingdom's religion.
Behind the scenes[]
The game incorrectly depicts the labarum as the sybol of Mithras. In reality, it represents the Greek letters ΧΡ as the monogram for Christ (in Greek: ΧΡΙΣΤΟΣ) and was adopted as a Christian symbol in traditional Christianity (Greek and Latin).
The labarum (Greek: λάβαρον) was a vexillum (military standard) that displayed the "Chi-Rho" symbol ☧, a christogram formed from the first two Greek letters of the word "Christ" (Greek: ΧΡΙΣΤΟΣ, or Χριστός) — Chi (χ) and Rho (ρ). It was first used by the Roman emperor Constantine the Great. Since the vexillum consisted of a flag suspended from the crossbar of a cross, it was ideally suited to symbolize the crucifixion of Christ.
It was an introduction by Emperor Contantine I around October 27, 312, preparing for the Battle of the Milvian Bridge. The Emperors identified themselves with the Mithraic title Sol Invictus, but other than that, the labarum was never historically linked to Mithras; and certainly the Romans who brought the worship of Mithras to Britannia were not the same Romans of Contantine I.