Greg Bahnsen was debating a hostile atheist in a university in California. The man asked a question that was a great blunder.
“Is your God invisible and immaterial?”
“Yes, He is.”
“Can you tell me of anything else that is invisible and immaterial and real?”
“Yes,” replied Bahnsen, “the laws of logic.”
The audience broke out into an enthusiastic applause. The atheist was unable to recover from his mistake the rest of the debate.