The Holy C was purchased back in the day.
Aside from that - part of the problem has always been the Pharisee. Monotheism was conducive to the goals of consolidating leadership under a single ruler from among clans/tribes. Tribal and family gods were replaced with a single, all-powerful god and the government in question was the will of that god. Worship and recognition of tribal gods was made heretical and seen as an act of rebellion against the state.
It's important to remember what Jesus was talking about when he delivered his woes unto the Pharisee. At that time, Judaism hadn't been formulated and the monotheism we know today was still in its infancy.
One could even go so far as to argue that Jesus was declaring the Pharisee to not even be of a proper blood line, though that is probably taking the argument a big too far - it is worth noting that the arabs we consider the jews today were not likely the descendants of Cain.
As for why this would control the clergy… Suppose you believed you were part of a higher entity and this entity was trapped, requiring certain actions to free? If you believed that you were a shard of Lucifer and that all of humanity could be reunited after a global war within that being… Then you might be willing to see the acts of sacrifice and war as lessons or necessary acts to make humanity whole.
People can get a bit weird when they start learning a bit too much of one side of the truth.
The church's population are planned sacrifices. Before one gets too bent out of shape over Cain being a murderer… One should remember he was a farmer and blacksmith. His brother, Abel, was the shepherd. What sacrifices do you believe each would have made to their god? If the clergy are shepherds …?
The good always outnumber the bad - but it is important to reflect on as you see the signs of the good struggling against the institutional policies of their order.