In situations like this it is often good to use the Socratic method wherein one asks questions. Thus you might ask, “Why do you not believe in God?” This will make the student reflect on his own motives and reasons and to make the case for his view. Suppose he says, “I don’t see God anywhere.” You might ask: “Why do you think that only things you can see exist? Can you show me evidence that unseen things don’t exist?” In other words, follow his train of thought and make him do the work to defend his position. Avoid mere gotcha questions, and when he might protest your many questions just reassure him that you are trying to understand why he thinks there is no God. Asking questions will help him discover some of the errors in his own logic. For example, saying God doesn’t exist because He can’t be seen is really a poor premise. There are many things I cannot see that do exist. I cannot see Topeka, Kansas, right now, but it exists. I cannot see an atom. These are real things, yet we know they exist by observing their effects. Many people use the Socratic method quite well in their conversations with atheists.