Will atheists cooperate with Christians to agree on concepts and rules for proving or disproving the existence of God?

I have discussed with atheists about the existence of God in web forums, and I have noticed that they don’t want to come to agreement on concepts and rules for proving or disproving the existence of God, like for example the very concept of God Whose existence they deny, and they don’t want to come to agree on rules to observe in proving or for them in disproving the existence of God.

Pachomius