With regard to all the world's religion having something to offer, well so does Harry Potter, or any the the millions of writers who have existed.

Religion, however, is full of horrific ideas, sending people to perpetual hell if they don't believe in Jesus or cutting off their hands if they steal in Islam.

The other problem is that most people are followers. They are not capable of independent thinking. Thus they do whatever the Imam, the Rabbi, or the priest tells them. As you have pointed out, there is nothing to stop evil (or stupid) people entering these professions.

Religions offer the non-thinkers and the weak-minded the following.

Comfort
Hope
Rules