Theology is NOT the study of one relgion. But don't take my word for it, take a look at any syallabus in any Universtiy in America.
And then you come back and apologise if you'd like. :-}
Wow.... you are right. I just went to a Dictionary; but you know how biased that can be. < /sarcasm>
Here's a hint click here.
As you apparently do not read the links, I'll copy it here for you.
1.) The study of the nature of God and religious truth; rational inquiry into religious questions.
2.)A system or school of opinions concerning God and religious questions: Protestant theology; Jewish theology.
3.)A course of specialized religious study usually at a college or seminary.