There are some fine distinctions, and probably a range of useful words.
Creationism tends to come in two forms.
- “wow, the whole thing is so complex and beautiful, there must be a higher being”
- “This large floppy book holds the entire perfect truth and it says God created everything.”
1 isn’t just the theory, it contains the premise and the conclusion and the deduction. I would call that the “logic” of the argument.
2 isn’t by any any useful definition of the word a theory. The usual word is “dogma”.
The creationist theory is simply that “a higher being created the universe.”
The “wow so complex” argument is, to a point, falsifiable - in that it predicts that there will be complex aspects to the universe that cannot come about by any unguided process. This can be refuted by showing how it is both possible, and how there is clear evidence, for unguided processes to have given rise to these complex entities (the Blind Watchmaker argument.) It is an ongoing process as adherents can keep coming up with new examples of complexity. Given that these examples continue to be refuted means the argument in favour of the theory is very weak.
Religious dogma isn’t a theory. It isn’t falsifiable, and makes no predictions. Nor is it in any way questionable or modifiable. Another phrase for it is “revealed truth”. Given that most creationists are really pedalling their version of Christian theology, they remain on very shaky ground in that they also need to explain where their particular large floppy book is right, and those of other cultures are not. This is partly why “dogma” is so apt.