Most theists can't. If they do it is usually very vague or incredibly self contradictory. They also seldom agree. Is he omnimax? Thus far in the other thread there is one theist who says no, a couple that don't know what omnimax means (sorry, my fault for not better defining) and the rest seem to suggest yes he is omnimax (though many qualify the term). It also seems to be common amongst some theists to define God as undefinable and beyond human knowledge. Whether or not there are things that are 'unknowable' about God doesn't release him from what we can know about him and his interactions with the physical universe. We do have conceptions of good and evil, physical laws, and the use of logic.
The root of this argument. Omnimax means God is omniscient, omnipotent and omnibenevolent at minimum. Some will further add that he is omnipresent, omnijust and a number of other omniterms. Omnimax by its straight forward definition is self contradictory so generally theist will define omniscient as knowing everything that there is possible to know, omnipotent as being able to do anything that is possible to do, Omnibenevolent still means morally perfect or all-good.
Objective Standard of Morality
Its seems most all theists believe an objective or absolute standard of morality does indeed exist. Rarely it seems they can agree on what that standard is and never have I been offered actual proof of its existence. Whether or not it is of God or independent of God is not often agreed upon by theists as well. The existence of such a standard of course means that Good and Evil (capitalized to demonstrate them as an objective concept) do indeed exist as well.
Most will say it exists, some will deny, definitions of it vary. Most often it is defined as the ability to choose freely. This is still left to speculation.
With the brief synopsis of what I believe most of us Evil Atheists see here so far on these boards I will put forth my first argument. I have seen all the above talked about in multiple threads lately and yet believe that all are in a sense interrelated and belong together.
Enough with the views, now for my arguments:
Defining God is the key to everything. You have to know what it is we are talking about and it also assigns the burden of proof. Many love to switch the burden to the atheist to disprove the existence of God or claim that the burden is equal. This is fallacious in nature and it comes down to who is claiming what. Positive claims about reality must carry the burden of proof. Some will claim that "There is no God." is in fact a positive statement that carries a burden of proof with it but they fail to see one thing. It is the theists that must define God. In defining God you are making the positive statement about reality and carry the burden of proof. Denying claims that have failed to meet a burden of proof are fully justified; even if the claim is true it is still more rational/reasonable to lack belief in them until evidence is presented in their support. Add to that; demanding evidence of the nonexistence of something is illogical. I can no more provide evidence for the nonexistence for God than I can for elves, fairies, antirgravity machine or 'Canadians that don't say Eh'; until a coherent definition is given, once again making the claimer of positive knowledge the one to go first. Once defined, even if god fails the burden of proof, atheists have a definition to work with to either demonstrate as impossible or further decrease the probability of said entity's existence.
Omnimax is usually how God is defined so I am sorry if I do not address you theists who think otherwise. More specifically theists generally qualify this definition as meaning All-Powerful - being able to do all things logically possible. All-Knowing - knowing all things logically possible. and All-Good which is morally perfect, only able to do good. This is opposed to the actual definitions of 2 of the above three words which are truly defined as being able to do anything and know everything. (For future reference I will use the All- terms to mean the 'watered down' versions of the Omni- terms.)
This whole concept opens up a can of worms for the theists. It all boils down to assuming things. Presuppositions. Theists generally presuppose God then try and reason their way too him assuming everything that is necessary to accomplish their task. They assume God exists, assume he is All-Powerful, assume he is All-Knowing, and assume he is All-Good and the use what they assume to assume what they wish to prove.
Theists claim that God can do all things logically possible. He cannot, for example, square a circle or create an unmarried bachelor; these things by definition alone are self contradictory. Yet anything that is thought to be logically possible; it is automatically assumed that God can do it. The problem here is the qualifier 'logically' before possible. Simply labeling something as logically possible means we can imagine it not that it is indeed possible. The fact that we don't know is exactly why we have to qualify it with the term 'logically'. I've used the example before about resurrection. It is thought by most theists, and many others that indeed resurrection is logically possible. I for one believe resurrection is logically possible. This does not mean it is; yet because it is thought to be logically possible it is assumed that God can automatically do it. It may indeed be an objective fact that resurrection is impossible. If resurrection is impossible, it is no longer logically possible. (Note, when trying to argue against this point realize the argument isn't directly about resurrection but about anything that is currently thought logically possible but in turn is actually objectively impossible).
By knowing that something is factually and objectively impossible, then you also know that it is not logically possible; it can never happen. The fact that we don't know allows us to label things that may be in truth impossible as logically possible. What does all this mean? By defining All-Powerful as being able to do all things logically possible you cannot merely assume what attributes that gives an entity. If resurrection is in fact impossible then God cannot do it and still meet your 'watered down' definition of All-Powerful. This though does not appear to be the same God propagated by the majority of theists. This well demonstrates that theists are merely assuming what it is they wish to prove.
Objective Standard of Morality leads somewhat of a trick question in and of itself. Did God (1)create it or does (2)it exist independently of him and he must abide by it?
(1) Well if God created it and if God is also All-Good then anything God does is good. This excludes the possibility of the existence of Evil. God is also usually defined as the creator of everything. It is a direct contradiction that something that is All-Good could create Evil. I'll further extrapolate after I cover point #2:
(2) If an objective standard exists and God is independent of it + must abide by it then his most popular definitions do not hold. There is something that the creator of everything (another attribute commonly included in the definition of God) didn't create. Not only that he is limited by it. If God is in fact All-Good and must abide to the absolute standard of morality then there is an entire array of things (Evil) that God cannot do. This is in direct contradiction with being All-Powerful.
OK, back to the first point. A God defined as creating an objective standard of morality creates the Problem of Evil (PoE). I've covered this recently in this thread. If God created everything then he also created what it is we perceive as Evil. How could an All-Good God create Evil? The most common answer to this is the Unknown Purpose Defense (UPD). This seems to be an argument that many theists agree appeases the logical aspect of this argument but it doesn't. Evil coming from something that is All-Good doesn't make any sense no matter how you look at it. Adding an unknown purpose only justifies the perceived Evil, in which case demonstrates that it wasn't actually Evil at all. In this scenario everything that happens is Good because it has an unknown moral purpose that justifies it. Therefore nothing we perceive as Evil is actually Evil and we have no way of knowing what Evil actually is. In fact it is impossible for Evil to actually exist because it is always justified by a moral reason (even if unknown) in order to keep our omnibenevolent God All-Good.
Free Will is often posited as a possible reason for the allowance of Evil on God's part. Several problems with this. Free Will would have to be demonstrated as good in order to qualify as moral justification for allowing Evil. Further; if Free Will is a good moral justification for the allowance of Evil you still have not escaped the argument in the paragraph above this. If Free Will is the reason then said perceived Evil is justified and once again not really Evil at all.
Another problem is Free Will contradicts All-Knowing. That is unless of course All-Knowing does not include the logical possibly of seeing / knowing the future. All-Knowing dictates predetermination. Free Will is not merely the ability to choose. If it were then the words 'ability to choose' would be adequate enough and the term Free Will need not be applied. Free Will means the ability to choose freely; to have more than one option all of which are possible. The problem: God created everything and knew ahead of time what all outcomes would be.
God could have created a world in which you chose to do B but instead he created a world in which you chose to do A. You may have chose A, but you were unaware that you had no other possible options. Only A could happen, all other options were impossible. If you only have one option that is possible, you do not have Free Will. God cannot create the possibility of you having Free Will unless he doesn't know what you will choose; if he doesn't know what you will choose then he isn't All-Knowing. God in fact must lack Free Will because he is All-Knowing; he already knows exactly everything he will do / create / think and is powerless to change it (which of course contradicts his All-Powerfulness). If he can change it then that dismisses his All-Knowingness.
The only way out of all the above arguments is to assume they are not true, assume they are not contradictory or assume words do not mean what they actually mean. Assuming what you wish to prove is a very poor way of debating and yet not much wiggle room has been left for the theists; yet they persist. Thats all for now, more later...