Disclaimer: This is a work in progress and is an analysis of the greatest works of Douglas Adams. It is my take and in no way confirmed by the author himself.
A lot of Christians seem to love the author Douglas Adams and his Hitchhiker's Guide to the Galaxy series of books. I've always loved them, even when I was a Christian. What I didn't realise back then was that Adams was an Atheist who was rather scathing of religion in general. What I also didn't realise is that his series of books pokes fun at religion mercilessly.
One of the major jokes in the book that has become famous throughout the world is the notion that the answer to life the universe and everything is 42. This joke here mocks creationism. As a creationist you automatically take the viewpoint that the universe was created by God. You then go out to support that viewpoint, whereas with science the questions come first and you search for the answers, no matter what they may turn out to be.
So in the Hitch Hiker's Guide to the Galaxy we see the Magratheans behaving exactly like Creationists and Begging the question. They create a computer which gives them the answer - 42 (God created the universe), and then create an even bigger computer to endorse that answer by finding out the question, which they never really knew to begin with. We see the same thing with creationists who automatically throw out any evidence that violates their belief that God created the world, while only holding on to apparent evidence that does.
And of course the irony is that the Magratheans are also the ones responsible for creating the Earth. They manufacture planets! And of course that there is to show just how absurd the idea is that there is any creator of planets.
The characters of the series are a jab at creationism too. Just look at Marvin the Paranoid Android. One of the first things we think when we come across this character is why the hell would anyone program a robot to be so cynical, depressed and miserable? But yet that's exactly what Creationists would have us believe when it comes to God creating us humans, i.e., that he would created humans with flaws. He created us with a human nature (which makes us inclined to sin), he decided which personalities to give us (which all have their negatives and positives), he gives us advantages and disadvantages. Some of us even get disabilities and it's all part of his design,. (Psa 139:13 For you created my inmost being; you knit me together in my mother's womb. Also Ex 4:11, John 9:1-3) So Douglas Adams has this character Marvin to show us just how ridiculous the notion is that a God would create flawed beings.
Speaking of Marvin, I see another great jab at religion in this character. Marvin shows us that eternal life is actually a curse, not a blessing. He claims to be ten times older than the universe itself, due to constant time travelling. He has the brain "The size of a planet" and knows everything there is to know. He's done everything there is to do. There is nothing now that makes life interesting for him. Imagine after several billion years of eternity . You will have done everything there is to do, you would know everything there is to know. Life would become dull and mundane, just like it has for Marvin. After several billion years you’ll be as miserable as he is!
I also like the fact that he finds the beauty of the world loathsome. Creationists often marvel at the world around them and how amazing it is, so it MUST be created. However as we see with Marvin, beauty is in the eye of the beholder. It's all appalling to him. Who's to say that there isn't alien life forms out there that would look at our planet and think "What a hell hole!"?
We also see Zaphod Beeblebrox a man who's decided that his body isn't good enough as it is, so gets himself a second head and an extra arm. Once again a dig at creationists who would claim that God's works are perfect. If we are honest with ourselves, the human body is far from perfect and has many flaws. We all have parts of our body that don't work as they should or we would like replaced or enhanced. There are many things in general about the human body that could be improved upon.
We also have the minor character; the Great Prophet Zarquon, who is an obvious satire of Jesus Christ. His followers have been waiting for thousands of years for his promised return. He turns up at the end of the Universe to rescue his followers from being annihilated. Unfortunately he arrives a few seconds too late and the universe is destroyed before he can rescue them. A great little poke at Christians who continually insist Jesus is returning, but he never does.
A little known character in the Hitch Hiker's series is Agrajag. Actually, he plays a bigger role in the series than you might think. He appears in the original story as the famous pot of Pertunias, which thinks "oh no, not again!" as it goes crashing down... along with the whale... onto the planet of Magrathea. You don't find out that's Agrajag until the book "Life the Universe & Everything". Agrajag is your classic example of how the notion of God having a plan for everyone is ridiculous. God's plan for Agrajag is to be reincarnated over and over as different life forms only to be slaughtered by Arthur Dent. Agrajag is even aware of his previous lives and has made it his mission to get revenge on Arthur who is totally oblivious to the fact he's been killing the same being over and over. The whole concept of Agrajag just shows us how stupid it is to believe that God's plan would be to have someone suffer or die in a particular manner. eg to have a baby born and then die in its first few days.