Reddit mentions of The Coherence of Theism: Second Edition (Clarendon Library of Logic and Philosophy)

I think the best thing to do here (especially if you enjoy reading) is to do some study into the good reasons why Christianity is believed to be correct. William Lane Craig's Reasonable Faith is one of the best, most cohesive defenses of the reasonability of the Christian faith I've ever read but there are plenty of other good sources too (Richard Swinburne's The Existence of God and The Coherence of Theism, J.P. Moreland and Bill Craig's Philosophical Foundations of a Christian Worldview, Paul Copan and Bill Craig's Come Let Us Reason, Craig Keener's Miracles: The Credibility of the New Testament Accounts, and Alvin Plantinga's Warranted Christian Belief just to name a few).

You might be familiar with some of this already, but I'm going to explain it as though you have no familiarity with this subject.

Philosophy of religion explores topics such as the existence of God, concepts of God, religious language, religious belief, miracles, and so on. Philosophyofreligion.info presents a good primer for the subject.

It seems like your primary interest is in the existence of God. Natural theology, although the approach of doing theology without the assistance of special, divine revelation, in philosophical circles is basically synonymous with arguments for the existence of God. Natural atheological arguments, as some have put it (i.e. Plantinga), are arguments for atheism.

Popular arguments for the existence of God would be the various cosmological, teleological, ontological, and axiological arguments. There's almost too many of them to keep track. Popular arguments against the existence of God would be the various kinds of the problem of evil, divine hiddenness, and attacks on the coherence of theism.

"The Blackwell Companion to Natural Theology" is perhaps the best single resource on arguments for and against the existence of God, although it is highly advanced. "The Cambridge Companion to Atheism" is also a very solid resource. "The Existence of God" by Swinburne is classic, as is his "Coherence of Theism." Again, all of those are fairly advanced. Swinburne has a shorter, more popular level version of "The Existence of God" titled "Is There a God?" Stephen Davis also has a similar book titled "God, Reason and Theistic Proofs." If you're going to be reading Oppy and Sobel, I recommend reading their counterparts in any of these books above (barring the "Cambridge Companion to Atheism," of course), that way you have a good balance of perspectives.

With regards to the philosophy of religion a bit more broadly, William Rowe, C. Stephen Evans, and Brian Davies each have solid, brief introduction books. Michael Murray and Eleonore Stump have a more thorough introduction; Louis Pojman and Michael Rea have a great anthology; and William Lane Craig, J. P. Moreland, and Michael Rea have perhaps the greatest single resource on this subject.

Moreover, William Lane Craig has dozens of debates on topics concerning the existence of God (and other topics) available on YouTube. Here is a fantastic list of his debates with links available in the table. You'll see some popular figures in the list that aren't good philosophers (i.e. Sam Harris, Christopher Hitchens, Lawrence Krauss, etc.), but there are quite a few very high caliber philosophers on that list too (i.e. Michael Tooley, Quentin Smith, Peter Millican, Stephen Law, etc.).

Let me know if you have any other questions.

Good luck!