Trust in the Lord:
Logically, good is better than evil. If an evil god is doing something bad, it's only bad because there is a law that god is breaking. It can only be breaking a law if there is a law. So if there is an evil god, and he is breaking the law, then he can only be breaking God's law. Which means if an evil god exists, then God exists.
This, I think, highlights some of our differing assumptions. You say logically good is better than evil. I would argue that we call things good when we think positively of them, and call them evil when we think negatively of them. Which is slightly different.
More importantly, you assert that something is only bad if it's breaking some law, and that there can only be a law if there is a good god. I disagree with both of those. I don't think a "law" is required for something to be bad or good, and I don't think a good god is required to make a law. A while back I asked you if you thought it would be wrong to rape a child for fun if God told you to do it. You said, no, if God said to do that, it would still be evil. Which is great, because we both agree on that. But the question is, what would be evil about it, in your view? You had said that it would be wrong because it caused suffering and pain, if I recall correctly. Notice that you didn't appeal to any law or the opinion of any god to say that. You were able to decide that if God said "rape kids for fun," that He'd be evil for saying that, without requiring some other god to make a "no raping kids" rule. So, I would say that by the example of your own reasoning in answering that question (reasoning I agree with, by the way), you've demonstrated that the reasoning you've used in the above quote is wrong. An evil god could exist, without require some different god to exist. So your logic here fails, as you have demonstrated with your previous answer. So we need a bit more to answer the question.
Lastly, even with the problematic logic, you didn't fully answer the question. Your conclusion was that a good god exists. But you didn't yet specify how you could tell which was good, and which was evil. If one says "Do X!" and another says "Don't do X!" and both are claiming to be good, how do you know which is correct?
Trust in the Lord:
Additionally, if there is a supreme evil god, who made laws to break, if this evil god exists, why would he allow good?
Perhaps or the same reason that a supreme good god, who made laws to follow, would allow evil? In order to be truly evil there would need to be free will, or something like that, I guess. It's a legitimate question, but it works both ways. If "he wants you to have free will!" is a good reason for a good god to allow evil, then it also seems like a fine reason for an evil god for allowing good.
But if that doesn't satisfy, perhaps he's just a capricious god? Maybe he wants to confuse us? Perhaps he needs the glimmer of hope in order to cause true pain and suffering? Take your pick, really. As you mention, this is a thought experiment, and this isn't a crucial aspect of it.
Trust in the Lord:
Then if there is no situation that would make it good, it is objectively evil.
As I've pointed out many times now, we're using the word "objectively" differently, and had probably best avoid it to keep from confusing one another. If that's what you consider objective to mean (that Tycho thinks it's wrong in all cases), then that's great, and it's "objective" in that sense. When I talk about it being subjective, I mean something very different than that, but I've been trying to avoid those terms, since I know it only adds to the confusion.
Interestingly, I also consider murdering captive women and children to be wrong in all cases. Which, from what you're saying here, makes it objectively evil. And yet you tell me that when God tells you to murder captive women and children, then it's not evil to do it. Which gets to the heart of two points I'm trying to make:
1. People can and do disagree about what they view as "evil."
2. Because of your acceptance that everything that God does is good, you can't tell if God is actually good or evil. You can literally defend the murder of helpless women and children as being "good," just because He told you to do it. When you reach the point where you're defending murder of kids as good, I think it's pretty clear that you've thrown the ability to tell good from evil out the window, and are purely down to "just following orders."
Trust in the Lord:
I think logic points out that good is better than evil, and therefore if evil, this being cannot be god.
Tycho:
And how can you tell if they're evil?
Trust in the Lord:
Because of Jesus
You'll need to explain that a bit more? You mean because of what Jesus said was good or evil? How do you know that he's right about that? If Jesus said "raping children for fun is good" would you know it was true because he said it? If not, that implies that Jesus saying something doesn't automatically make it so, so you need more than just his say-so to judge it. But what?
Tycho:
If an example would be easier to understand, consider this argument:
"Allah is, by definition, worthy of worship. Anything else is imply not Allah. What the christians call 'God' is not Allah, and is therefore not worthy of worship."
That's the exact same reasoning you're using. The only difference is which deity you consider to be worthy of worship "by definition." And the important thing to point out, is that because you've assert this "by definition" you can't say "well, obviously God is the one that's worthy of worship, because He did X, Y, and Z," because that's not "by definition." That's judging God based on His actions (which, is what I'm saying we should do).
Trust in the Lord:
Ok, I disagree. I feel that the bible supports God through history, and prophecy, while the koran has some clear untruths in them, and lacks prophecy.
Good, good! But the counter is "Oh, so since Allah doesn't behave how you want him to, he can't exist? Since he doesn't give you the prophecy you want, he can't be real?" ;) (real question, by the way, though with a grin)
But more seriously, now you're not using the "by definition" you mentioned before. Here you're arguing why Allah isn't worthy of worship, which you can't do if we accept him as worthy of worship "by definition." But if we don't do that for Allah, it seems that we also shouldn't do it for God. Here you seem to have changed to arguing that God is worthy of worship because of what the bible says. Which means, it would seem, looking at the bible, and evaluating God's worthiness based on what the bible says. I would argue, then, that looking at bits where it says He orders the murder of children and thinking "hmm, doesn't seem like the kind of chap I'd like to worship, really" makes a lot of sense.
I feel like you're trying to have it both ways here. On the one hand, you want to say God is good by assumption, so we can't judge Him negatively for anything He is said to have done. But on the other hand, you want to use what other deities are said to have done in order to judge them. You've got one standard for your god, and a different one for all the others. And that type of reasoning is what blocks you off from ever knowing if you're wrong. If a muslim does the same thing (holds Allah to one standard, and God to another), he'll never convert because he's made Allah always right by assumption in his mind, and God is "bad" by nature of simply not being Allah. That kind of trap, where once you're inside a belief system you can't get out, is something I think most religions aim for, and is what I think is most important to avoid.