Ditto to MineralMan.
I think that talking to atheists is like talking to anyone else. If you do so with respect, you're likely to earn respect in return. I love having philosophical conversations with my church-going friends (one of whom is a Baptist minister) and wouldn't dare disrespect their beliefs. I do, however, ask the same in return. ;)
I do not think Newdow is capable of showing respect to anyone.