this answer is a bit lengthy, sorry in advance 😅
"religious symbolism and imagery" can contain any portrayal of religious themes or symbols that would pertain to religion in general. those themes can be inspired or based on existing religions or made up ones. in general, it's all up to the creator, and you can be as vague or as specific as you'd like. for inspiration's sake, a few examples for the inclusion of "religious symbolism and imagery" are:
• in the characters (gods/deities, angels/demons, other non-human beings, prophets, priests, religious leaders and figures, etc);
• in objects (books, attires, jewelry, rosaries, "shrines", sanctuaries, religious art/sculptures/figures, candles, etc);
• in events or rituals (weddings, sacrifices, baptism/initiation rituals, prayers, masses, religious gatherings, etc);
• in the setting or environment (temples, churches, heaven, hell, purgatory, spiritual realms, etc);
• or even with the trope itself (myth/fable/story retellings, metaphors, reincarnation, afterlife, corruption, conversion, etc).

lastly, i'm very sorry about the delay anon! hope i helped!!