I think you can either believe in something or not, if it is a specific thing. Of course, you can have different opinions on the matter than other people, but that still means you believe in that topic. With Conor, he is almost certain that his mother is not going to die, that the medication is going to help and it will make him all better, in this case, he falls between believing and not believing. In my opinion I think he knows that his mother is going to die, he is just going through the denial faze of grief even tho she hasn’t even died yet. He even said to his dad how he would like to move america, which is him saying that of course he is not okay with it happening, but at this point it is the inevitable.