I found out the hard way, they debate not to gain more believers but rather to destroy the Christian Faith. By destroying the Christian Faith
only then can they justify their religion and atheism is a religion.
True, but in the process they do actually end up dragging blind followers over to their side, which is why it's important for believers to get the truth out.
The atheist I'm thinking of has a large audience (would never name him here as he's quite dangerous, particularly to those who are here searching), and while his goal is clearly to attack christianity, you just never know who is listening to those debates that end up wanting to know more about Jesus as a result.
I've noticed he's budged on some of his views over the last several years. Some things he denied back then he now accepts, and I really think he's on a journey which will eventually lead him to Jesus. He does actively seek out debates with christians and by now has probably noticed we all say the exact same thing, despite never having met each other.
Unfortunately I know of one person that became convinced by what he said, and could not wait to tell me. He emailed to say he was leaving his church because he thought this guy made some very good points. He even tried to push those beliefs on me. Very sad