All Good or All Powerful
Those who believe in god hold the idea that god is both all powerful and all good, but this is flawed. By the evidence of world events and the nature of reality, god must be one or the other, not both. If god were both, children wouldn't be born with tumors and cancer, if both, innocent people wouldn't suffer from natural disasters that wipe out millions, and on and on. A god would have the ability to stop these things from happening because of his goodness and power. Either one is true and one is false, or their both false, they cannot both be true.
Let's assume that a god is all powerful and that it created the universe. We know that the universe is a harsh and miserable place where destruction is rampant and frequent (every second of every day). Stars explode, galaxies collide, planets are destroyed by meteors, and all of this takes place without rhyme or reason. The creator would have to take responsibility for all of this, it started the universe that exercises destructive behavior in the first place.
This creator will also have to take responsibility for the inevitable destruction of Earth and this Milky Way galaxy-the sun is destined to swell up, burn this planet to a crisp, and we are currently on a direct collision course with the Andromeda galaxy. When galaxies collide, two things generally happen: they will merge and form a larger galaxy, or they will completely destroy each other and spread their contents into the vast expanse of space. With either one of these scenarios, life as we know it on this planet will be destroyed. How can a god who is all good create something destined to destroy us in the most violent possible way?
If a god were all good, babies wouldn't be born with aids, unless it was powerless to stop it. If it were all powerful, it would be indifferent to good and evil, and let things play out however they may (the kid with an ant farm analogy). The evidence shows that we live in a universe that came about spontaneously, from nothing, and it doesn't care whether or not we like what it does, there is no mind behind any of it.