[gcruse]

(1) If God exists then he is omniscient, omnipotent and perfectly good.
(2) If God were omniscient, omnipotent and perfectly good then the world would not contain evil.
(3) The world contains evil.
Therefore:
(4) It is not the case that God exists.

And if he is neither omniscient, omnipotent, or perfectly good ... who needs him?

[frogjerk]

Good reading: http://www.newadvent.org/summa/100203.htm

[Havoc]

Your conclusions do not logically follow.

[Grut]

If someone only helps us we may like him very well but we will have no idea of whether or not we love him; we only discover that when he harms us and we find it within ourselves to forgive him.

It's a very simple idea: God puts evil in the world to make the knowlege of love possible.

[Mad Dawg]

(2) If God were omniscient, omnipotent and perfectly good then the world would not contain evil.

I think you skipped a step or two here. What is "evil" anyway? Maybe it's good that the world contains evil.

Think a minute. If something is less than "perfectly good", what is the imperfection?

At a hazard, it looks like your argument comes down to "God is allowed to create only God, with respect to perfection."