Nothing is a better way of wasting our precious time than watching a stubborn Christian debating an arrogant atheist. The conversation will simply start like this:
Christian: "please say this prayer and you will go to heaven."
Atheist: "wow, you believe in god?"
On the other hand, a conversation between an open-minded Christian and a knowledgeable atheist can be the best intellectual feast you can ever get. There are a good number of open-minded Chrstians in our societies. I personally know many. Knowledgeable atheists are far fewer. You can roughly classify the atheists in our society into three categories (WARNING: possible stereotyping, my apologies first)
1. The social "outcasts"
These are people who don't give a **** about god because they don't give a **** about everything. They are the hippies on the street and druggies in a public hospital ER. Asking them to give you a presentation on atheist is pointless, even though they come, because the Christian can simply say "just watch, this is what becomes you when you give up God."
2. The previous Christians
These are people who were once Christian but decided to switch to atheism. Most common reason is tragic life experience (God failed me). They are mostly people who live a healthy life. However, they are not likely to give a good atheist presentation because most of them just want to stay away from spirituality. A lot of them tend to be agnostic rather than atheist.
3. Active Atheist
Atheists in this category make an informed decision about atheism, which I believe is the cardinal feature of a strong atheist, that is, they voluntarily make the decision of not believing in God after exploring Christianity throughly. These atheists have a better understanding of the Scripture than most seasoned Christians. I am a strong atheist and I read the Bible very frequently, whenever I'm free. You would be like "what the heck, an atheist reading bible?" Well, if you don't even know what Christianity is, how do you refute it? That's like saying you hate pizza before you've ever tried pizza. An active strong atheist also has a solid understanding about the debate of Creationism vs Evolution, which is a whole new topic and very profound. Becoming a qualified atheist of this kind requires years and years of reading, researching, thinking, and communicating with both atheists and theists.