Praying for something, like requesting gods to grant power, has different levels and success rates.
The powerful ones are like Charlette, who can even pray for a god to descend directly upon herself, although this is because her nature has begun to resemble the divine, allowing her to bear the god's power.
The weaker ones, such as the most ordinary believers, can pray to the gods three times a day with utmost sincerity, but even after ten years, the gods may not respond.
Of course, if you have a talent for practicing Divine Art during this process, you might already be a bishop of a region, and that's a different concept altogether.
But in a certain sense, Mohe's constitution completely rejects the divine power; her body flows with the distilled blood of the Demon King, inherently repelling the power of the gods. This is why, even if the ritual succeeds, Mohe can forcibly interrupt it, causing failure.
If you replace her with someone else, the consequences would be dire.
