Interesting Painting

So one of the prop makers for season 1, had this photo to share, of a briefly used section of part of a Mithraic temple. I am curious to know what the painting in the background means.

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https://preview.redd.it/3m9kjbar6ym91.png?width=1467&format=png&auto=webp&s=59adb73709924b4a8b0aaef71a37eb16faec063f