@markoos,
First, are you talking about a dissertation or a thesis? You probably mean a thesis because a dissertation requires doctoral candidacy, which in turn requires a preliminary thesis developed by you and your assigned mentor before your application for examination can be approved. If you are asking a general question about "what kind of thesis have you done," I did a fundamental analysis of Aristotle's Metaphysics Zeta from book 1 to 10 based on David Bostock and Richard Hopes translations my senior year. It was very arduous and took two consecutive classes to do (one for the class and the other as the subject of my capstone thesis).
On Hume's critique of beliefs applied to religion, there's a ton to write on. In order to talk about Hume's theory of belief, you have to first examine the nature of cause and effect, which was Hume's primary aim in both
Treatise of Human Nature and
An Enquiry Concerning Human Understanding. You would need to at least talk about the relation between cause and effect. And this is
at least. Take into consideration
Enquiry 4.4.1, where it says that in order for us to exercise our understanding, our minds require the seven "reasoning" relations: resemblance, identity, space and time, quantity or number, quality or degree, contrariety, and cause or effects. What you should come to as a conclusion is that a cause is always necessary. From the inference of that cause, you can then explore Hume's notion of belief.
What you are looking for is specifically located in
Treatise on Human NatureTreatise 1.3.7.2, where we have basically come to the understanding that our belief in existence brings no new ideas to those which in a sense form the idea of the object (GOD). Hume says it best by saying, "When I think of God, when I think of him as existent, and when I believe him to be existent, my idea of him neither increases nor diminishes." (
Treatise 1.3.7.2) This is in a sense the center point for you and your goal of linking belief with God (the theological aspect). After that, it all depends on you whether or not you want to elaborate more on impressions and ideas, vivacity, etc. You can also go into the cause of belief in
Treatise, 1.8.3.2 and the influence of belief, which actually was formed as a precursory note in
Treatise Treatise with what is in
Enquiry.