This is a great illustration from an article by Fred Zaspel on 1 Corinthians 1:18:
Harry Ironside told the story of the time a famous atheist publicly challenged him to a debate. Ironside’s response was interesting. He did not turn the man down. Nor did he accept outright. Instead he responded with a challenge of his own. He told the man that if he would bring just one man and one woman who had formerly been an outcast and worthless to society but who had been transformed, restored, and made a value to society again as a result of hearing the atheist’s message, then he would be glad to debate him. And for his part, Ironside said, he would bring a hundred such men and women. The atheist, of course, declined.