Hierarchy works well in a stable environment.
Hierarchy is is much reviled in the present day.
Any great organization can go through sectarian phases.
An escalating, violent tit-for-tat may lead to terrorism.
Pretensions to moral superiority are devastatingly destructive.
Islam is in principle egalitarian, and has always had problems with power.
When we are reflecting on terrorism we can grieve for many things we do and have done.
If you want to change the culture, you will have to start by changing the organization.
It's unlikely that the organized religions will get more sectarian... or is it? I am not at all sure.
It seems true that the growth of science and secularism made organized Christianity feel under threat.