Andrew Arensburger explains How Not to Embarrass Yourself in an Argument With an Atheist:
Fortunately, for religious arguments, there is a simple technique: take your original argument, substitute some other faith, and see how convincing it sounds to you.Let’s take, for example, the argument that “Millions have found purpose in life through Jesus. Their lives have been enriched beyond measure by the Bible.” This is undoubtedly true, but just how convincing is it to someone who isn’t already a Christian? To find out, let’s turn it around: “Millions have found purpose in life through the prophet Mohammed. Their lives have been enriched beyond measure by the Koran.”
Now raise your hand if you’ve just had a sudden urge to convert to Islam. I said, raise your hand if… anyone? No? Hmmm…
All right, what about “The Bible is thousands of years old. There must be something to it, for it to have survived that long!” Once again, let’s turn that around: “The Tao Te Ching is 2500 years old. There must be something to it, for it to have survived that long!”
Doesn’t really want to make you want to rush out and become a Taoist, does it?