Omniscience: the capacity to know everything infinitely, all knowing, infinitely wise...
This is a trait often attributed to deities. The Christian god is no exception. Yet is seems that the words of believers and their own holy book fly in contrast to this claim, as I will illustrate.
Free Will: Many a theist will tell you that God has a perfect divine plan for us but that we also have free will. Meaning that we may make choices that go contrary to his plan. The problem here is that if he is omniscient, before he ever makes us or the plan, he already knows what choices we will eventually make. This voids any perceived choices that we may appear to have. He literally created you knowing what your choices would be and then created a plan knowing what you choices would be. So the idea that we have real choices within the plan that will determine our fate voids the claimed omniscience of said deity.
Tower of Babel: I've discussed this one on here before. But in this story, the people plan to build a tower to Heaven. Well God was worried that they would succeed. Worried!?! Surely and omniscient deity would know beforehand that they would fail... Know that Heaven is not literally atop the clouds... Know that current building techniques would allow them to get nearly that high, and that if the tower hot high enough that the thinner air would prevent the workers from going any further.
Facts: One would expect an all knowing deity to realize that Pi does not equal three, and that bats are mammals and not birds. Theses are just two simple fact that all school children should know, yet an all wise deity seemingly does not. There are certainly more, but I feel this is enough to illustrate this point.
Age Restrictions: This is a question that came up in a discussion on another site. A theist asked that why it is in chapter six of Genesis that God says that no man shall live past 120 years. But after that there are people that live past that age. The theistic explanation given is that at the time everyone was too wicked and God didn't expect anyone to be righteous enough again. Yet these people eventually did come along and surprise the lord, and he made exceptions in their case. Didn't expect? Surprised? Again, if said deity we truly omniscient he would know that these righteous people would exist before he ever thought of setting such an age restriction. Staying within the confines of the religion, this either tells us that God was lying or is not omniscient at all.
Tests of Faith: We've all heard it before. The lord is testing your faith. Whether it be Abraham being asked to sacrifice his son or simply having tough times at work, someone has stated that our faith is being tested. Yet there is one enormous problem with this hypothesis. An omniscient god would have no need to test ones faith. To send misfortune and see how we react or if we even go so far to turn from god for being slighted so. No, an omniscient deity would only have to look into us and would know how we would react to such events and simply see the true feelings and amount of devotion inside of us. This is also part of the problem associated with Pascal's wager. It is asserted that paying lip service to belief is better that being open about non-belief. In lay terms, faking it. Yet this again ignores God's pro ported omniscience. For if he truly was all knowing, he would know you weren't sincere in your belief. Making the wearing of such a false facade pointless.
Communication/Prayer: I have also been told by theists that the reason a non-believer or future non-believers prayers are not answered by God is that he can not hear the prayers of the unrighteous. Again, this flies in contrast with his claimed omniscience. For if he can not hear the thoughts and prayers of everyone, he can not know all. Furthermore, these same people have even told me that he can't make himself heard to those that don't believe. This would additionally speak toward God also not being omnipotent... But that is not the subject of this particular blog.
Church Status: My wife and her mother were talking the other day and the pictures we are having taken came up, along with the fact my wife and I will NOT be in the church directory. My wife was baptized, 1st communion and confirmed. She was even a catechist for a bit. I went to CCD and had communion, but that's as far as I got... Well her mom was saying to her that "Well, you're still a Catholic"... In an attempt to get her to be in the directory. My wife replied that she actually isn't, she's a Wiccan. Her mom said, 'yeah but you're still a Catholic though'. She then reiterated that technically shes excommunicated because as far as the church is concerned, she practices witchcraft. Her mom continued that it was still okay because the church and/or preacher doesn't know, so she still has time to 'grow up'. Not wanting a fight, she simply said that if her mom really wanted to be a true Catholic is was her duty to report beliefs to the priest and that she put a lot of thought into leaving that church and arriving at her current belief. That she is not Catholic, but Wiccan. As is always the case, I was absent for this discussion. My wife says that it's because her mom is afraid of the logic and facts that I would bring to the discussion. I would not have been as kind as she was though. I would have had to bring up a huge problem with her stance of the preacher doesn't know so the church doesn't know. That problem is God himself. It is after all said to be 'God's church'. Well, if he is truly omniscient he would know that my wife is Wiccan and not Catholic. By the rules of 'his' church she is guilty of witchcraft and condemned to excommunication whether on paper on Earth or in the mind of God.
I do find it amazing how often the Bible and it's believers will contradict this initial trait that they always apply to their god. Not only does it go on to disprove parts of said god, but begs the question. If we can know so much that God can't, then how can we call him God? We certainly can't say such a being is perfect and the loss of this trait erodes a substantial portion of his pro ported abilities and power.