I tend to avoid arguments that can't possibly convince my opponent, though if the objective is to convince a neutral third party I guess that might be a promising argument.
The other side of that sword is that the personal religious experience argument isn't especially convincing to others, either.
One way of proceeding to argue with it, for example, would be to say, "how do you know you're not mad?".
[Amusingly half way through writing this comment, this radio programme started: http://www.bbc.co.uk/ahistoryoftheworld/objects/pZ-Jq-iaTOia... It's about an object that apparently people used to use to talk to god!]