Arguing with an atheist - an exercise so futile that it might make
you start to question the existence of God
In the end, if people's views are so deeply entrenched that there's no flexibility in their thinking, having a discussion with them is just going to be a frustrating, energy-sapping waste of time if their views are diametrically opposed to yours - and that applies to
any argument, not just theological debates.
If you do find yourself wanting to argue with a person like that, I think it would be more useful to examine
why you want to argue with them, what it is that's driving that desire; what tends to drive human behaviour a lot of the time is unfelt, unresolved emotion, so pay attention to what's happening in your body, notice where there's constriction, resistance, heaviness, etc., and allow your body to let go of what's it holding on to if you can.