Looking at Our World
The level of design in nature implies that there must be a creator God. We have to explain how we think the complex world in which we live came into being. Naturalists (atheists, or materialists) would argue that since energy is able to enter our world, and the building blocks of life were already present, it is possible for chance collisions of molecules to produce life.
But such an explanation has many problems. For instance, although energy is free to enter the system of our world, what mechanism connects the energy to the work of ordering chaotic molecules into the precise, complex order needed for life? Organizing matter into meaningful structures that compose living cells requires information. Random arrangements accomplish nothing. And randomly assembled molecules cannot evolve because they lack the ability to replicate themselves. The whole complex mechanism involved in DNA and protien synthesis would be required before natural selection could ever come into play. Theists argue that such complexity could only arise as the direct result of intervention by someone with purpose and intelligence.
Suppose we put some dynamite under a pile of bricks, and blew it up. The system contains sufficient energy and the correct building blocks to build the Taj-Mahal. But is it really likely that blowing the bricks up would have this result? Even if we repeated the experiment millions of times over, it seems unlikely that it would ever result in the Taj-Mahal, or any other kind of building. Even though the building blocks and energy are there, more is needed. The energy has to be channeled in a very precise way in order to produce a very complex design.
People like to refer to the famous experiment where amino acids were produced in a bell with gasses similar to what may have been present on the early earth. But this is really irrelevant. Amino acids are simple molecules that would have to be arranged in a meaningful way by the thousands just to get a single strand of DNA. This would be like blowing up the brick pile, and afterward finding that one brick had landed on top of another. Someone might cry out, "Look! If these could self-assemble, that implies that the Taj-Mahal could self-assemble too!" But no. The two bricks don't imply that at all.
Of course the more complex the design, the more difficult it is to believe that it happened by accident, and living organisms are much more complex than the Taj-Mahal. Wouldn't it be easier to believe that someone acting with intelligence and purpose has arranged things this way?
Such an argument cannot prove that a personal God exists. This is because some parts of the argument are subjective. For instance, what constitutes order? Isn't it our observation of an existing system, and our labeling it as orderly that makes this argument seem so plausible? This may be partially true, but in many of our minds, we have adequate reason to consider things like living cells to be orderly, and orderly in a way that could never be explained by simple natural processes such as those put forward by naturalists so far.
God says in the Bible that the argument from design is cogent and convincing. (Romans 1:18ff) Once we understand the argument from design, we can develop the even more interesting presuppositional argument.