All wordly religions are an instrument of power.
The ultimate purpose of religions is always to make you surrender.
There is no limit in the means that can be used as long as the goal is met: Make you surrender and not question things.
While goverments use primarily military and economic influence to rule people, religion sets itself higher by claiming to be a representative of a higher goverment by gods or one god. Religions gain power primarily through making people feel guilty or induce fear in them. After enough people were converted violence can be used as well, but that method is not very sustainable and many religions do not use that method.
Religions gain power through the human mind and are more sustainable than nations, since they are not limited to nations and can survive even after being conquered.
Religion is the highest form of a power system. It is driven by the most intelligent people, the priest class and the less intelligent people cannot even think of a method to defend themselves, that is why it can be so powerful.