This article first appeared in edited form on CNN and is printed below in its entirety.

When I was diagnosed with cancer, the question "Why me?" was a natural one. Later, when I survived but others with the same kind of cancer died, I also had to ask, "Why me?"

In my last post, I made an argument for why we still need apologetics. Believing has both a head and a heart aspect, so while some non-Christians will need more help with one than the other, we can’t ignore either one.

So what can we say when we are called upon to present the reasons why we believe?

First, I try to show that it takes faith to doubt Christianity, because any worldview (including secularism or skepticism) is based on assumptions. For example, the person who says, “I can only believe in something if it can be rationally or empirically proven” must realize that that in itself is a statement of faith. This “verification principle” cannot actually be proven rationally or empirically, making it an assertion or a claim, not an argument. Furthermore, there are all sorts of things you can’t prove rationally or empirically. You can’t prove to me that you’re not really a butterfly dreaming you’re a person. (Haven’t you seen The Matrix?) You can't prove most of the things you believe, so at least recognize that you have faith.

Apologetics is an answer to the “why” question after you’ve already given people an answer to the “what” question. The what question, of course, is “What is the gospel?” But when you call people to believe in the gospel and they ask, “Why should I believe that?” —then you need apologetics.

[This was previously posted on Redeemer.com.]

I find it frustrating when I read or hear columnists, pundits, or journalists dismiss Christians as inconsistent because “they pick and choose which of the rules in the Bible to obey.” What I hear most often is “Christians ignore lots of Old Testament texts—about not eating raw meat or pork or shellfish, not executing people for breaking the Sabbath, not wearing garments woven with two kinds of material and so on. Then they condemn homosexuality. Aren’t you just picking and choosing what they want to believe from the Bible?"

Ross Douthat’s Bad Religion attributes Christianity’s decline in the U.S. to: 1) the political polarization which has sucked churches into its vortex, 2) the sexual revolution that has undermined the plausibility of Christian faith and practice for an entire generation, 3) the globalization that has made the exclusive claims of Christianity seem highly oppressive, 4) the materialism and consumerism that undermines commitment to anything higher than the self, and 5) the alienation of the cultural elites and culture-shaping institutions from Christianity.