[Serious] What God's justification for eternal torment?

[Angrboda]

If there is no absolute moral authority, then there is no good and evil, these words become basically undefined, because human beings as moral agents with limited information will forcibly disagree on the list of moral/immoral actions.
By contraposition, if there is good and evil, there has to be an absolute moral authority.

Even if there is an absolute moral authority, which there's not necessarily good evidence for, that does not provide any reason why that moral authority must reside in a God, much less your God. So even if I grant absolute moral authority exists, your conclusion is a non sequitur. Morals could be an objective feature of the universe apart from any God. And if there is no absolute moral authority, that would not mean that the terms good and evil have no meaning and become undefined, but rather simply that they do not have the meaning that you seem to want to insist they must have. That's a misapplication of the law of the excluded middle.