Pastor Tim Keller of Redeemer Presbyterian Church in NYC emphasized the importance of rational arguments for Christian faith, saying that "gospel-shaped apologetic" must "challenge the non-believer's worldview and show where it, and they, have a real problem."

In a blog post on Tuesday, Keller stated that believing has both a head and a heart aspect, and "we can't ignore either one."

Like Us on Facebook

"So what can we say when we are called upon to present the reasons why we believe?" the megachurch pastor challenged Christian readers.

Since any worldview is based on assumptions, "it takes faith to doubt Christianity," Keller said.
Even when someone claims that “I can only believe in something if it can be rationally or empirically proven,” that statement itself requires faith, for it cannot be proven rationally or empirically, Keller explained.
In other words, that "verification principle" is self contradictory.

Keller quoted C.S. Lewis' self question before his conversion, which is stated in "Mere Christianity" as follows,
“But how had I got this idea of just and unjust? What was I comparing this universe with when I called it unjust? …Atheism turns out to be too simple.”

" You can only judge suffering as wrong if you’re using a standard higher than this world, a supernatural standard," Keller continued.

"If there’s no God, you have no reason to be upset at the suffering in this world. That’s just the way it is. It takes faith to get mad at this world."

In the post, the pastor made the case for apologetics, or what apologist William Lane Craig defines as the branch of Christian theology which seeks to provide a rational justification for the truth claims of the Christian faith.

What apologetics aims to do is to answer the "why" question, said the author of "The Reason for God: Belief in an Age of Skepticism."

Rather than telling people what to believe, "a gospel-shaped apologetic" must show the non-believers "their real problem," Keller asserted.

"In this case we are showing secular people that they have less warrant for their faith assumptions than we do for ours. We need to show that it takes faith even to doubt," Keller explained.

"A campus evangelist I once heard during the Vietnam protests pushed atheist students to recognize the clash between their moral relativism in regards to sex, and their moral absolutism with regards to international genocide," Keller raised an unbeatable example, regarding the Moral Law, which Christians believe as the absolute God-given morality that tells the right from the wrong.

"If there’s no God, everything is permitted. Without God we’re left with no basis for all that is most important to our lives: human dignity, compassion, justice. We have a problem," Keller explained.

"There is a way of telling the gospel that makes people say, 'I don’t believe it’s true, but I wish it were.' You have to get to the beauty of it, and then go back to the reasons for it," the pastor advised Christians.

"Only then, when you show that it takes more faith to doubt it than to believe it; when the things you see out there in the world are better explained by the Christian account of things than the secular account of things; and when they experience a community in which they actually do see Christianity embodied, in healthy Christian lives and solid Christian community, that many will believe," Keller concluded.