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
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 this 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. I normally make this point by considering an objection to Christianity, to show that at the heart is some sort of faith assumption.
Let’s take the example of suffering—someone will say, “I can’t believe in God, because how could a good God allow such suffering?” Put another way, they are saying, “I know for a fact that there can’t be any good reason that a good God would allow this specific thing to happen.” Really? There could be all sorts of good reasons why God allowed something to happen that caused suffering, despite our inability to think of them. If you’ve got an infinite God big enough to be mad at for the suffering in the world, then you also have an infinite God big enough to have reasons for it that you can’t think of.
Arguing with God
You have to show people that it takes faith to doubt Christianity. C. S. Lewis argued with God before his conversion that the universe seems so cruel and unjust. But then he asked himself, “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” (Mere Christianity, Book 2, Part 1).