Carl Sagan is perhaps best remembered as the host of the PBS series, Cosmos, but another, enduring legacy he left us is his analogy, “The Dragon In My Garage.” I invite you to read it for yourself but here's a summary. Sagan claims to have a fire-breathing dragon in his garage and invites you to see it (he refers to the reader in the second person, “you”). However, when you enter the garage, you see nothing. Sagan then claims the dragon is invisible. So how do you know it's there? You think of a few possible ways to try to detect the dragon: flour on the floor to see if it leaves footprints, spray painting the dragon to make it visible, or an infrared sensor to detect the heat from its flames. However, Sagan has an excuse that shoots down each experiment: the dragon flies so it doesn't leave footprints, it's incorporeal so paint won't stick to it, and its flames don't produce heat.
The story is meant to be an analogy of how atheists see Christians' belief in God. It's clever in a couple of ways. First, Sagan predicts a few possible objections to his argument and attempts to address them in the story. This isn't necessarily novel since most apologists will try to consider possible objections to any point they make, but the fact that Sagan does it here shows that he thought through his analogy a little better than the ordinary critic.
The other clever thing that Sagan does in his story is refer to the reader as, “you.” By doing this, he attempts to put the reader in the shoes of the atheist, making him sympathetic to the atheist's plight. He's very complementary to the reader, making him feel very fair, open-minded, and inquisitive. The reader almost forgets that the skeptic in the story represents atheists! Sagan deftly paints atheists as being painfully open-minded and their skepticism as being healthy, ordinary, and rational. Also, since Sagan makes himself the keeper of the dragon, he is able to portray Christians as deranged or delusional without seeming to direct these insults toward them.
Consider these two quotes from the story:
Imagine that, despite none of the tests being successful, you wish to be scrupulously open-minded. So you don't outright reject the notion that there's a fire-breathing dragon in my garage. You merely put it on hold.
… the only sensible approach is tentatively to reject the dragon hypothesis, to be open to future physical data, and to wonder what the cause might be that so many apparently sane and sober people share the same strange delusion.
Do you see what I mean? “You” (reader) = atheist = enlightened thinker; Sagan = Christian = loon. It's clever to the point of being maniacal. I can almost hear Sagan laughing as he wrote it, “bwa ha ha!”
I disagree with his characterization of atheists. It's been my experience that atheists in general aren't merely withholding judgment about the existence of God until they see more evidence. Instead, they reject a priori any possibility of there being a God. Any evidence for God, like miracles, is rejected in favor of a natural explanation – even in those instances where no natural explanation exists. Dawkins, for example, would rather believe that life on earth was planted by aliens rather than believe God created life. Some atheists go even further. Rather than simply not believing in God themselves, Dawkins, Myers, and others of that ilk openly mock and ridicule the idea of believing in God. They aren't anything like the friendly skeptic in Sagan's story, optimistically looking for any evidence for the existence of the invisible dragon.
Regardless of how clever the analogy is, it fails on the grounds that it doesn't accurately represent the way Christians believe in God. In other words, it's a straw man. There are several subtle ways the story is wrong but the primary error is this: Christians don't ask people to believe in God while offering excuse after excuse why there is no evidence that He exists. To the contrary, Christians offer many reasons why people should believe in God and it's the atheist, the supposed “open-minded” skeptic in the story, who rejects them one by one.
First, God is revealed in His creation. The simple fact that the universe exists strongly suggests there is a cause behind it. To believe that God is the First Cause seems far more reasonable than believing that the universe just poofed into existence without a cause. Furthermore, the universe doesn't just exist, it's also sublime. The enormity, the beauty, and the complexity all suggest design. Design always suggests purpose, purpose always suggests intent, and intent always suggests a designer. To believe that “uncaused” matter randomly, purposelessly arranged itself into the complex cosmos is far less credible than believing it was intended to be so by the design of an intelligent Creator. The existence of the universe and the design of the universe is evidence for God whether or not the skeptic wants to accept it.
But the greatest evidence for God is the Bible. While the universe might reveal there is a God, the Bible tells us Who He is. The Bible is a written record, the testimony of people who were first hand witnesses to God. These are the people who have heard His voice and seen His miracles. He is Jehovah of the Old Testament, the One Who spoke the universe into existence; He is the God of Abraham, Isaac, and Jacob; He is the One who delivered the children of Israel out of Egypt and made them a great nation. He is also Jesus of the New Testament, the I AM Who was before Abraham; He walked on water, calmed the storm, healed the sick, and raised the dead; He shed His blood on the cross as the payment for our sins and, three days later, rose from the dead; He now sits at the right hand of the Father making intercession for us.
The words and miracles recorded in the Bible bear witness that there is a God. Critics are welcome to suggest natural causes for the miracles. They're welcome to suggest the history of Bible is somehow not as trustworthy as other books of antiquity. However, they cannot credibly say the Bible cannot be considered by Christians to be evidence for God.
There are more things I could discuss as evidence for God but it really isn't necessary. The analogy fails. No matter how cleverly it was written, it doesn't accurately represent Christians, nor does it fairly depict how skeptics evaluate the evidence for God. It's a straw man. It has endured only because it is an amusing straw man.
If the only thing that would convince someone that God exists is that he saw Him with his own eyes, then perhaps he will be disappointed because that's not likely to happen. Even so, I suspect that even if it did, it wouldn't convince some people anyway. Regardless, there is plenty of evidence for God available to anyone who truly seeks Him.