The moral argument, for atheism!

[Mr.wizard]

I do understand reductio absurdum but my point is that if god is the author of morals and he must be good then he can not make a moral decision that is bad. Meaning that making the decision to not inform us must be good as we established in premise. Therefore a god who is the source of morality, who is good, and who chooses not to inform us could in fact exist.

In premise 2 she is asserting that it is a real, moral obligation that would exist.  You can deny that premise if you like.  But arguing that the premise is contradictory to the supposed nature of an all good God is simply asserting the possibility of it being otherwise, not pointing out an actual inconsistency in her argument.

Why would the obligation exist? God is the author of morality!

The argument is stating that god makes the rules and he must be right.
Then you are saying well he must make this rule or he is wrong.

He cannot always be right and be wrong, especially if he is the one determining what is moral.