Here’s a note from Francis Schaeffer on the point of contact between Christians and non-Christians:
“As a Christian approaches the non-Christian, he still has a starting place from which to know the person in a way that the non-Christian does not have, because he knows who the person is. One of the most brilliant men I have ever worked with sat in my room in Switzerland crying, simply because he had been a real humanist and existentialist. He had gone from his home in a South American country to Paris, because this was the center of all this great humanistic thought. But he found it was so ugly. The professors cared nothing. It was inhuman in its humanism. He was ready to commit suicide when he came to us. He said, ‘How do you love me, how do you start?’ I said I could start. ‘I know who you are,’ I told him, ‘because you are made in the image of God.’ We went on from there.”
“Even with a non-Christian, the Christian has some way to begin: to go from the façade of the outward to the reality of the inward, because no matter what a man says he is, we know who he really is. He is made in the image of God; that’s who he is. And we know that down there somewhere – no matter how wooden he is on the outside, or how much he has died on the outside, no matter if he believes he is only a machine – we know that beyond that façade there is the person who is a verbalizer and who loves and wants to be loved. And no matter how often he says he is amoral, in reality he has moral motions. We know that because he has been made in the image of God. Hence, even with a non-Christian, the Christian has a way to start, from the outside to the inside, in a way that non-Christians simply do not have” (p. 82-3).