Many people love to conflate the words theory and hypothesis. I assure you, in the language of science anyway, they do not mean the same thing.
The first step of any scientific theory is to propose a hypothesis. Once this hypothesis is verified, it becomes a theory. In order for a hypothesis to become a theory, it must make falsifiable or testable predictions. It must have a minimum empirical basis to be considered a theory. It must be consistent with aspects of any and all pre-existing theories that have been experimentally verified, or must experimentally prove that such aspects are/were incorrect. It has to have multiple strands of evidence – not just one single foundation – confirming it to be the best possible approximation or correct in its entirety.
Therefore, when you hear someone say that something is “just a theory,” let them know that essentially what they’ve just said is this: “It’s JUST been verified using the proper channels of the scientific method. It’s JUST been experimentally proven. It JUST has several strands of evidence to support every aspect of it.” When you say it like that, it doesn’t sound so much like the word “just” should really be in these sentences, does it.
You certainly never hear people denying gravity or thermodynamics, do you? Of course not. Why? These disciplines and studies are rooted in theory, so why should they be any more applicable than evolution, anthropogenic climate change, the estimated age of the earth and the universe, or any of the other issues people tend to have with science – mostly for religious reasons? There is no answer to that question, simply because they shouldn’t be put on a separate pedestal. A theory is a theory is a theory, and in science you can take a theory to the bank, or else it wouldn’t be one.
For this reason, can we please stop using the term String Theory? String Hypothesis does not under any circumstances fall under the umbrella of the term scientific theory. You may reread the second paragraph above, and you will notice several areas of the demanded criteria of a bona fide scientific theory that string hypothesis does not meet. If we in the scientific community were to quit conflating the scientific usage of the word theory with the general usage, perhaps our enemies would be less able to conflate them. If you mean hypothesis, then say, “hypothesis.” If you mean theory, then say, “theory.”