I don't think they do.
I think that most people hear what they want to hear, listen to what they want to listen to, read things that confirm their views and don't seek out other views.
People have biases. We all do. Including you.
People are just lazy thinkers, especially when it comes to forming opinions.
But when asked to explore their opinions, they can change. I think your opinion changed because initially you said it was an attack specifically in Christians but you now say that no one really knows yet why the attack was carried out. You reflected and your opinion changed.
But people are lazy thinkers.