Looking for tips and ideas for an upcoming debate

Hello there.

Tomorrow I'm gonna be having a debate/discussion with a fellow atheist in front of 80-100 people, about the merits of religious beliefs.

From what I know, the position she wants to argue for is that maybe sometimes, for some people, religious beliefs are a good thing, or at least provide some benefit. They give hope, make sense of the chaos and absurdity of our lives, and that when you look at it, religious people seem more united, calm, and content.

I have to argue for the opposite. Personally, I tend to agree, or at least be in the middle on this. I think the world will be a better place without religion overall, but when I'm confronted with a lot of the religious people around here, the argument that they "need" their religion is hard to escape.

I guess I'm just looking for general tips and tricks and ideas about what I could bring to the table in order to make it an interesting and informative discussion.

Thanks :)