- The God Hypothesis - Dawkins contends that if god really created life, then who created god in the first place? He goes on to remind us that the whole problem we started with was to explain the statistical improbability on the origin of life. Thus it makes no sense to take the god position because there is the larger problem of who designed the designer. In comparison, evolution by natural selection becomes a more probable and hence preferrable theory.
- Evolution of complex organs is possible - creationists argue that complex organs like the eye could not have evolved in a piecemeal fashion over time. This is because the eye is made of several critical parts without one will cause the entire system to fail. Dawkins counters by pointing out that the eye could actually have started out as a simple light receptor. Having a light receptor is definitely better than nothing when you are in the wild searching for meals and trying to avoid becoming someone else's meal. What came next were the functions of focus, colour, etc., each of which brought additional advantages that were perpetuated by natural selection.
- Abundance of Goldilocks planets in the universe - Creationists claim that the conditions necessary for life to exist on Earth are so unique that it must have been the work of a supernatural god. Earth is a Goldilocks planet, because we are at just the right distance from the sun to support carbon-based life forms. But Dawkins maintains the Earth is not that special after all. Contemporary astronomical data suggest there are about 1 billion stars in our galaxy. Orbiting these stars are another 1 billion to 30 billion planets. Look farther out and it is estimated that there are close to 100 billion galaxies in our universe. Let's err on the conservative side, knock a few zeros off, and say there are just 1 billion billion planets in our universe. Suppose the rise of life from spontaneous generation of DNA material, being highly improbable, only happens on one in a billion planets. With these odds, you can still expect to find life on a billion planets throughout the universe. Given the unbelievably large playing field the universe offers, it is almost illogical not to expect life on other planets.
Though none of the above concepts are bleeding edge, Dawkins does a great job using everyday language to argue his case. If you want to learn a few things on atheism vs theism, this is a good introductory read. Make sure you get your facts right however and not just rely on this one book. As the saying goes: when one person suffers from a delusion, it is called insanity. When many people suffer from a delusion it is called religion.