In the minds of many Christians, this is exactly what can never be admitted. To admit that they don’t know the answer seems like defeat, so it is best never to admit that you don’t know an answer. However, the refusal to admit ignorance has two negative effects on the apologetics encounter.
First, it leads some believers to bluff, which when attempted with a knowledgeable unbeliever, does serious damage to the credibility of the gospel. What does this bluffing look like? It may be something like making up statistics or claiming to have read a certain philosopher or scientist when you really haven’t. It may be making claims for Christianity that are simply not factual. Either way the Christian is acting dishonestly and risking the integrity of the gospel.
Second, refusing to admit that you don’t know the answer to an objection gives an unbeliever the impression that the Christian faith is to be held blindly. If an unbeliever knows I don’t know the answer to her question, and I refuse to admit it, she will think Christians hold to their beliefs despite the lack of evidence. This is exactly the distorted definition of faith that Richard Dawkins accuses Christians of practicing. The truth is, rather, that our faith is built on historical fact and divine revelation, and we shouldn’t believe firmly anything that is not informed by those sources.
Why, then, should we be quick to say, “I don’t know”?
First, it is intellectually honest. There will be MANY times that unbelievers will ask questions that blind side you. There are a million ways to suppress the truth and a thousand challenges to the Christian faith. It would be nigh impossible to have an answer for every conceivable objection that could be raised.
Second, demonstrating that you don’t pretend to be omniscient will often win points with an unbeliever. Christians are often perceived to be arrogant (sometimes rightly so), and by admitting you don’t know an answer, you demonstrate genuine humility, which may shock your unbelieving conversation partner. Remember, the skeptic’s argument against Christianity is not always (or even often) intellectual. Sometimes they object because they have never met a Christian they liked. By admitting ignorance in response to a hard question, you make yourself more real, and therefore, likeable.
Finally, admitting you don’t know something allows you to follow up with the unbeliever. Since evangelism is best accomplished as an ongoing relationship, telling an unbeliever that you will have to get back to her, and when can we meet again, allows you to continue defending and commending the faith. This also allows you to turn the tables on your conversation partner by being the one prepared to discuss a topic you have studied, while she may struggle with the answers you have provided. And that’s a good thing—to make the unbeliever squirm, I mean—because quite often squirming leads to more questions. The more questions you answer, the fewer obstacles will stand in the way of saving faith. So, by admitting you don’t know the answer may actually result in more unbelievers finding eternal life in Jesus Christ.
And all this begins with an honest, “I don’t know.”