Religion cannot provide morality

Using the Argument from Morality to prove that religion cannot provide morality, in a fictional dialogue.


Atheist: What if I came up to you and said "okay, I had a dream and I figured out how everyone should live, all right, and I wrote it down in this book. Now do what it says". Would you do it?
Theist: No, of course not. Why should I believe you?
A: Okay. But what if I hold a gun to you, and you don't have any, and tell you to obey what the book says?
T: Then I would pretend to obey you until I could find a way to stop you.
A: Good, good. What if a space alien came down to Earth and told you that they made up a book of rules that humans should follow, and demands that you obey them?
T: I'd say that they don't have dominion over me. I should be able to judge for myself.
A: What if they say they will incinerate you if you don't obey?
T: Then it would be a situation of force again. I would obey but they wouldn't be moral. I think I know where this is going.
A: Where is it going?
T: You're going to ask me about God, and ask me to justify why I think the Bible is a good moral code, when it's just God's opinion. And then you're going to talk about Hell.
A: That's right! For a Christian, you're smart! So tell me, why should you believe God's opinions when you don't believe mine, or those of a space alien?
T: Because God created everything. He would know better than me what is good and what is evil. Besides, everyone is born evil and needs God's rules.
A: How do you know that?
T: Because it says so in the Bible.
A: How do you know that?
T: Because the Bible is correct.
A: You have no way of knowing that the Bible is correct. You could very well have been made to believe a lie by God. God is omnipotent, why couldn't he be tricking your mind?
T: But God is good and would never do such a thing.
A: How do you know that?
T: Okay, we already talked about that. I know that God is good because it says so in the Bible.
A: And you assume you know it says so in the Bible because you assume God is good. So you can't really answer my questions? If you can't, then you have to admit that there's no difference between God's arbitrary rules and anyone else's.
T: You're being childish. I believe in a good God and that's that!
A: How do you know that it is what you actually believe?
T: Because without this belief, life makes no sense.
A: How do you know that you need this belief for life to make sense? Life makes sense to me and I don't have the belief. God could be deluding you into believing that life makes no sense without believing in him.
T: My head is spinning.