Some atheists claim that religion is the one. Some theists claim non-religion is the one. Some people think the nuclear bomb is the one. Others think the nuclear bomb is necessary, thus it is a response to other things that are scary. Some people think that missiles are the scariest invention of mankind, while others call some missiles "peace keepers". Some people thought in history, the "lightning bringing stick" referring to the gun as the one. Some others may think a rebellion is the one.
What do you think is the scariest thing mankind ever invented? Why do you think that is?
I assume, when you say "scary" you mean that has the most potential for negative use?
In my POV religion is far far behind in relation to nuclear knowledge.
It is even farther than the threat of AI.
People who use religion to control people, are the same kind of people that will use technology, politics, money, and any other mean they have in order to gain control.
You could say, that many religious people, for their own better understanding of their religion, they should learn more about how things work in reality.
Religion is going through evolution, just as any other thing we know, life, language, social behaviors. it all works the same.
Take it to whatever you wish from there, but the fact is this is how things work.
I see it that way... if you fear non religion or religion, you are basically missing a lot out of the whole.
same goes for any other fear, if you fear rich or poor, you are missing a lot out of the whole.