Unlike other religious organizations, the Temple of Death didn't have a sacred maiden and couldn't produce any Champion of God. Hence, they somewhat lag behind other big religious organizations in terms of building power.
Although they could be said to be the most influential and wealthy religious organization, they are still nothing in front of absolute strength. In Firuman, the war between religious organizations is more brutal and ruthless than conflict between nations.
The religious organization always preaches the same thing and makes the people believe in their God. It is not rare if they have a conflict between one with the others about whose God is right or wrong.
Since the World Alliance never truly steps in for their conflict, they fight without restraint until death. If the Temple of Death loses their credibility and reputation, the other big religious organization will definitely use this opportunity to attack them.