Referring to the ‘origin of life’ specifically but yes theories are guessing or making things up. But some guesses are better than others and origins of life guesses are far out there(calling origin’s ideas ‘facts’ is just silly) . But they do get the creationists worked up. Not sure if origins fit in ID or not.
Sorry, your conception of a scientific theory is incorrect. That may be the way a layman uses the term, but in science a theory is very much more formal. Here are some definitions that may help:
Theory: a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena; "theories can incorporate facts and laws and tested hypotheses." Addendum: "Theories do not grow up to be laws. Theories explain laws." (Courtesy of VadeRetro.)There are more definitions on my FR home page.Theory: A scientifically testable general principle or body of principles offered to explain observed phenomena. In scientific usage, a theory is distinct from a hypothesis (or conjecture) that is proposed to explain previously observed phenomena. For a hypothesis to rise to the level of theory, it must predict the existence of new phenomena that are subsequently observed. A theory can be overturned if new phenomena are observed that directly contradict the theory. [Source]
When a scientific theory has a long history of being supported by verifiable evidence, it is appropriate to speak about "acceptance" of (not "belief" in) the theory; or we can say that we have "confidence" (not "faith") in the theory. It is the dependence on verifiable data and the capability of testing that distinguish scientific theories from matters of faith.
Guess: an opinion or estimate based on incomplete evidence, or on little or no information.