[This section is provided as a public service. Feel free to distribute freely, so long as you give me credit for it.]
Judging by the number of people on the streets preaching the gospel of Jesus, there seems to be a fair amount of interest in converting people to Christianity. In light of this, it is interesting that any number of other religions still exist; Christianity is not universally accepted as the One True Faith.
Why is this? I suspect that the answer lies, at least in part, in the fact that many Christians find the tenets of their faith so blindingly obvious that they have trouble "stepping outside," so to speak, to see what their arguments look like to non-believers.
Imagine that you are at a party one evening, and it turns out that one of the guests doesn't believe that the sun rises in the morning. How do you convince him? Of course the sun rises! But it's so obvious that it's hard to prove. You could say, ``the Earth rotates, so that the sun appears to rise above the horizon.'' Is that a better or a worse argument than ``I've seen the sun rise many times''?
It's as plain as the nose on your face, but just like your nose, you might need a mirror to see it.
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?
And what about that hoary old chestnut, Pascal's wager? For those who aren't familiar with it, it goes like this: we don't know whether God exists or not, so you have two choices: to worship God or not. If you worship God, then either He exists and you win eternal life, or He doesn't and you haven't lost anything. If you don't, then either God exists and you lose big time, or He doesn't, and it doesn't matter. Hence, if you worship God, then you can't lose; if you don't, you can't win.
One of the problems with this argument is that it doesn't specify any particular religion. This argument applies equally well to Jesus, Allah and Krishna, not to mention Odin, Zeus and Pirun. How does it convince someone to become a Christian, and not a Jew or a Buddhist?
Also, don't forget that atheists don't believe that the Bible is divinely inspired, since they don't believe in God in the first place. So any argument based on the assumption that the Bible is the word of God is going to fall flat. For example, ``The Bible contains many examples of prophecies that came true. Surely, this means that it is of supernatural, if not divine, origin'' might become ``The Lord of the Rings predicts several events, such as the death of Boromir, the reapparance of Gandalf, and Aragorn's ascension to the throne, which later come true. Surely it must be of supernatural origin.''
Likewise, ``Jesus loves you and wants you to be happy'' is as convincing to a non-Christian as ``Barney loves you and wants you to be happy.''
Now, how about a counterexample? One show on National Public Radio featured a doctor who had written a book on the healing power of prayer. He described a number of studies, at least one of which was written up the highly-respected New England Journal of Medicine, that showed that patients who were prayed for tended to do better on average than ones who weren't. He said that the researchers had specifically considered psychosomatic effects: in one such study, the first names of half of the patients were given to organizations that pray for patients; neither the doctors nor nurses knew which of their patients were being prayed for, and the people doing the praying did not know anything about the people they were praying for. And yet, the group that was prayed for did better than the control group. In fact, the radio guest added, this effect is not limited to people: if people prayed for a specific bacterial culture, that culture would tend to grow faster than one that wasn't prayed for.
If you turn this around, say by replacing ``praying for Bob'' with ``standing on one foot and writing `Bob' on a piece of paper,'' and assuming that the facts check out, then this still remains a good argument. It may not make you want to run out and convert, but the next time you're sick, you might at least want to think about asking someone to stand on one foot and write your name on a piece of paper.
See also Ebon Muse's How Not to Convert an Atheist.