Classic Christian apologetics (the defense of the gospel) usually follows a two-step methodology:
1. Is there a God? [Spoiler Alert] Answer: Yes
2. Which One (or Ones)? [Spoiler Alert] Answer: The God progressively revealed in the Old and New Testaments and finally and ultimately in Jesus Christ.
If you are interested in a systematic presentation, I recommend you get ahold of Norman Geisler's Christian Apologetics.
I don't have the book in hand but, call me lazy, here's a ready-made review from Amazon by Bruce H. (Toronto, Ontario, Canada).
Here's Bruce's review [editted for length by the Ball Bounces].:
Geisler's evaluation of atheism is very well done (Geisler summarizes his section by saying that most atheistic critiques of Christianity or arguments for atheism are either self-defeating or can be turned into arguments for Christianity). Geisler provides a very through critique of agnosticism and shows that it is intellectually bankrupt.
There are three Parts to the book:
Methodology (approx. 35% of content)
Theistic Apologetics (approx. 29% of content)
Christian Apologetics (approx. 30% of content)
The Methodology section is about forming an adequate test for truth. This was an unusual section and it seemed to be unnecessary to spend so much time on it. A brief discussion (i.e. 20 pages) ought to be sufficient. Geisler's two tests for truth are very uncommon; unaffirmability as a test for falsity and undeniability as a test for truth. He rejects most of the better truth tests (e.g. combinationalism) for numerous reasons, one of the most common being that the test fails to establish one view over all others. However, this section did have good critiques of skepticism, agnosticism, and fideism; this is the most useful part of this section.
The Theistic Apologetics section was probably the best in the book, in my opinion. Geisler surveys and evaluates the following worldviews:
Geisler offers several reasons to reject the first four options, however I think it is unfair to exclude the first three simply because they are not theism. To be fair, Geisler does offer several other reasons to reject these philosophies.
The Christian Apologetics section [includes] a defense offered for the general historical reliability of the New Testament, the authority of Jesus Christ (e.g. by His sinless life, miracles, resurrection), and the authority of the Bible.If you are interested, wander over to Amazon and check out the Table of Contents. Highly Recommended. Alternatively, you might want to check out Dr. Geisler's site, here.