This video is lengthy, but great.
As our culture is becoming more and more bombarded with myriads of belief systems, there are good reasons to develop a reasonable apologetic for the Christian faith. That is, you better know why you believe what you believe. It is our responsibility to do so. We are called to be able to "give an account" for why we believe what we believe.
Of course, there are good, good reasons for the existence of God. However, you're not going to win over a skeptic of the faith by proving the existence of God by way of the Bible. . .skeptics today don't believe the Bible. We cannot use the Bible to prove the Bible, as it were.
So, we need to start at even a more foundational place with people in order to help them come to understand practically that there is a God. The older Christian apologetic books like Evidence that Demands a Verdict often assume that the reader has at least some respect for the authority of the Bible. Today that is not as true as it was thirty years ago. The arguments (I mean that word in the best sense) that we have for our faith need to be sourced in the reasonability/plausibility of the existence of a God. In fact, there is good reason to see that being an atheist actually requires more faith than being a Christian.
What Keller is brilliant at is entering the predominate belief systems of the day and showing that those systems are often self-contradictory and collapse on themselves. . .they require great faith to believe in.
Here is a great conversation with a tough interrogator who is asking some deep questions about the Christian faith. Not only does Keller answer thoughtfully and thoroughly, but with civility and kindness.