Everyday Evangelism- The Atheist Challenge!

I rarely encounter Atheists when I preach the Gospel, at least not in this part of the country where I live. There is a man on the other side of the country who has responded to a message of the Gospel that I put in a message bottle that goes out to a virtual sea in Facebook. He opened the bottle and responded by telling me that my god does not exist, and that is the happiest news ever. Well, I responded by asking him what proof he has that led him into Atheism. He said that it is obvious that there is no evidence of God, and that the proof of burden is on me. This is a new one for me. Help. You can't prove God from a scientific experiment anymore than you can measure the color of an apple. They are in 2 different categories. This discussion has been ongoing for over a week now and the man continually rebuts whatever I say by saying there is no evidence of a god. Basically I am the one who is blind because I can't see that. My god is imaginary. Well, I left him with the concept of the fact that he is blind because the light that he had at one time is taken away from him. Not only does he not have eyes to see with, but even what light he had has been taken away. What does one do with such a person? Any comments?