Before handing the person over to Moulvi lets give it a philosophical try, however superficial.
Does God exist?
If we question, does God exist, then we already conceive and understand every single word in the question before it is made a legitimate inquiry. Since the word ‘God’ already used in the sentence it necessarily assumes that it was understood what it stands for. So, we are compelled to admit that such a being does necessarily exist since it was already in inquirer's mind.
If we tell in our heart that there is no God, we could not really understand what was said in the heart. Since experience was necessary to raise question whether God exist or not, we know it a priori, the very idea of God.