Let's start with a belief. A belief is some firm, set view. View, opinion and belief are very close together. In fact, I almost see view and opinion as the same thing. But belief is a firm, set view. We can have a lot of views and opinions but they aren't totally set yet. They can be pretty strong but not yet set. Christianity and Judaism have a belief, there is a God. It's not just a view, it's a belief, it's very strong, it's set. So in my understanding a view is an opinion but it's very strong, it's set.
As to theories, in my opinion a theory is something we consider but we know it may not be true. We're actually theorizing when we think science or think of mathematics. Generally when they establish a theory they work towards proving it or disproving it so they can throw it out as false or keep it as a truth, if it's true. So a theory to me indicates that we're not freezing this view and we're going to challenge this view. We're open to seeing if it is true or if it is not true. So in this way a theory is more open, a belief is very closed, and views and opinions really basically include both of them.
A view can be mild or very fixed, an opinion mild or very fixed, but when it's very, very closed and set the view and the opinion become a belief. It would be far better for all of us not to have views, opinions and beliefs unless they're founded in truth.
A belief, founded in a truth, of course is different. I believe it's sunny today - this is my belief. Can you prove me wrong? Of course not, because it's actually sunny today. But generally when we think of the word, beliefs, these are things that we simply believe but we don't know if they're true. And indeed this applies to all of the theistic religions.