The following arguments against the existence of God are legitimate.

I had been waiting for some time to accept my first debate here, but circumstances (school, tennis, policy debate league, etc. ) had thus far prevented it. In order to empirically disprove the existence of God, one would have to occupy or observe every part of space all at one moment. Obviously, this is not possible to do, unless one were to become God, which is not something many atheists desire to do. However, it is universally accepted that if the definition or attributes of something are self contradictory, it is logically impossible for it to exist (ie. a square circle). My opening arguments, therefore, will concern the self-contradictory nature of the Christian God. I shall begin with a classic argument. God cannot be omniscient, omnipotent, and omnibenevolent at once. "Is God willing to prevent evil, but not able? Then he is not omnipotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Then whence cometh evil? Is he neither able nor willing? Then why call him God? " – Epicurus The fact that evil exists disproves the possibility of a God who knows that evil exists, has the will to stop it, and the power to do so. Additionally, omnipotence directly contradicts other attributes of the Christian God such as Holiness, Immutability, Eternality, and ultimately itself, thus making omnipotence paradoxical and therefore impossible, even excepting the contradictions with other divine attributes. God is Holy, meaning without sin. More than this, Holiness is the inability to sin. (Hebrews 6:18, "it was impossible for God to lie"). If God is unable to sin, than surely he is not omnipotent. God is Immutable, meaning unchanging. If God desires to change, could he do so? One might ask why God would have the Will to change, since it is seemingly a whimsical desire that God ought to be exempt from. In addition to failing to solve the paradox (it is a red herring argument), this raises another serious question that I will come to later. God is Eternal. If he wished to destroy himself, could he do so? Then he is not omnipotent. Finally, omnipotence itself asks: could God create a rock so heavy he couldn't lift it? The Theologians answer no; God cannot do anything that would contradict his nature. This paradox itself, however, is a direct contradiction of God's nature. Theists often use the Teleological argument (from design), which can be stated as thus: 1. To exist, what is complex and precise requires deliberate planning and manufacture by an intelligent being. 2. The universe is complex and precise. 3. Therefore, the universe was deliberately planned and manufactured by an intelligent being. Of course, it is not only the universe that is complex and precise, but the God that supposedly created it. Since God, by definition, has no designer, he cannot exist. By changing the form of the argument from modus ponens to modus tollens, we arrive at this result: 1. What is complex and precise requires deliberate planning and manufacture by an intelligent being. 2. God cannot, by definition, have been designed or planned by another being. 3. Therefore, God is not complex or precise. 4. Therefore God cannot exist. The obvious objection is this argument creates the paradoxical situation whereby the universe itself cannot exist; however, I shall address this in the following argument. Another common theistic argument is the Cosmological Argument. It has at least one unsupported premise and is logically a non-sequitur as well. Even if we consider it valid, the theist must admit that it is not necessarily a divine, personal God who caused time, space, and matter to exist. A modified argument, however, leads us to the conclusion that on the contrary, God cannot exist. For every effect there is a cause. Since every thing we observe is caused, we can determine a posteriori that it is impossible for something to be uncaused. This is so well established that many would contend that this is, in fact, a priori knowledge, exemplified by Newton's First Law (in the absence of force, a body either is at rest or moves in a straight line with constant speed), or that it is axiomatic. There must be, therefore, an unending chain of causes. God, on the other hand, is by definition uncaused. One might argue that God exists in a dimension outside of space, time, and matter where the laws of causality do not apply, however this is a fallacy known as special pleading, and thus God does not exist. The obvious objection is that the universe had a definite beginning, however, it would be more accurate to say that space, time, and matter have a definite beginning. They were caused by something apart from them, which, as per the Principal of Uniformity, we must assume, was caused by another, and another ad infinitum. Having covered generic arguments against the existence of God, I'll move on now to specific arguments against the Abrahamic God by showing contradictions, inconsistencies, and inaccuracies in the Old Testament that negate the possibility of its being divinely inspired. Pursuing further the argument against immutability, there are several passages in the Bible that contradict each other with regards to God's ability to repent (Numbers 3:19 "God is not a man that he should lie; neither the son of a man that he should repent;" Malachi 3:6 "For I am the Lord, I change not") while other passages show that God does, in fact, repent (Genesis 6:6 "And it repented the Lord that he had made man on the earth, and it grieved him at his heart"). In any case, the Bible is self-contradictory. The question of whether or not God can repent is a clear contradiction. God is stated to be all-knowing. This is well established in numerous verses, but what I am looking at specifically is Acts 24:4 ("and they prayed, and said, Thou, Lord, which knowest the hearts of all men. ") and Psalm 44:21 ("he knoweth the secrets of the heart. "). If God knows what is in every man's hear, why did he feel the need to tempt Abraham in Genesis 22:1? God should have known in advance what Abraham would do. Additionally, this contradicts another verse James 1:13 which states that God does not tempt man. Only an evil God would ask a father to do that; only a bad father would be willing to do it. This leads us to the issue of human sacrifice. In Judges 11:29-40, Jepthah vows to sacrifice as a burnt offering the first thing that shall come out of his house to greet him in exchange for victory over the Ammonites. His daughter comes out and he proceeds fulfill his vow. Clearly this is barbaric, as well contradicting Deuteronomy 18:10 "There shall not be found among you any one that maketh his son or his daughter to pass through the fire. " Finally, it is the default that it must be assumed that no God exists unless this can be proven, or at least shown to be more likely than the alternative. If one were to state that he has in his hand an invisible, immaterial ball, as per Occam's razor one ought to assume that this is not true unless it can be proven (or, as in the existence of God, shown to be more likely than the alternative). As Christopher Hitchens says, "What can be asserted without evidence can be dismissed without evidence. " Absence of evidence is indeed evidence of absence. I wanted to get into circumstances surrounding the Gospels and the divinity of Christ, but character restraints forbid it. Obviously my Biblical references don't need further citations. My logical arguments are based on reason and axioms, so I did not feel the need to cite them, however I will in the next round if my opponent should so desire. I'd like to remind the voters that I need win only one of my arguments to win the debate.