Hello there. Some contemporary philosophers say that Aquinas' arguments for the
I go on to recommend some other texts below and address the topic of philosophical disagreements and consensus, but first a comment on Stephen Maitzen's observation about not being under any obligation to believe either side in a dispute over theistic arguments. I am not disagreeing with Stephen on this, but I do wonder about the general point of when one might be obligated to come to terms (oneself) in believing one side or another in a philosophical debate.... Here is a suggestion:
Let's say you have been appointed the task of establishing a university in a developing nation in which there are different religious communities (Christian and Islamic or Hindu and Buddhist, for example). You have enough funds to establish sound programs in engineering, the sciences, languages...and now you are considering how much to devote to a philosophy department and, perhaps more specifically, you must decide whether that department or a religion department should include scholars who are well trained and are excellent in teaching who would be able to engage students (undergraduate and graduate) with arguments for and against theism or Monism, beliefs in Karma, philosophical investigations of faith and reason.... Imagine the decision is wholly up to you and (for some reason) there is no body of neutral "experts" you can consult. I think that under THOSE conditions, you may well have an obligation (as part of your task in establishing a university) to sufficiently inquire into the debates to see whether they can be carried out with fairness, skill, openness to listening and considering carefully to both sides. I suppose this is not at all a disagreement with Stephen, for I am not arguing that under those circumstances you would have an obligation to believe one side or the other. But you might have an obligation to inquire further into the debates until you are able to form a reasonable overview of the terrain...
In terms of further reading on theistic arguments, I would recommend the Stanford Encylopedia of Philosophy (SEP) entries on Philosophy of Religion as well as entries on specific arguments like the Cosmological argument. Oppy's book on Arguing about gods (recommended by Stephen) is brilliant in many respects, but I think it would be tough reading on your own; it is sometimes highly technical. There are some good recommendations in the SEP. I also co-edited The Routledge Companion to Theism (which Oppy contributed to) and this contains lots and lots of (what I hope you will find) interesting entries.
As for your general point about disagreements in the case of theism, I suggest that some disagreements in philosophy can stem, not from vigorous "objective" and "impartial" reasoning in which philosophers have enough time and energy to patiently review all the relevant arguments and objections. In this matter, theism is no different as a topic than, say moral realism (the conviction that there are moral facts that are as 'objective' as the fact that I am posting a reply to you now). Actually, topics in religion and ethics can be a bit more vexing than, say, philosophy of language, because the stakes are a bit high. Imagine that a philosophical argument in environmental ethics gives you convincing reasons to change how you live and what you eat and wear or whether you have children or adopt, etc... In matters of religion, some of those who grow up to become professional philosophers have had backgrounds in religion that are unfortunate (they were told to believe X on the basis of authority rather than good reasons) and this can taint one's interest in philosophically exploring religion as adults. So, background, time-constraints, patience or lack of patience... can all come in to account for there not being consensus (yet) in philosophy of religion and, I believe, in ethics, political theory, philosophy of mind and some other areas.
I hope we have not discouraged you from doing your own exploring of the philosophical literature. A nice pairing of opposing philosophers can be found in the book Debating Christian Theism.