Rhetorical: Amulek deals with the second accusation. Zeezrom used the device of claiming that Amulek was speaking for God as a means of shocking the audience and reducing Amulek's argument to an absurdity. Since Amulek had claimed authority through an angel, Zeezrom is attempting to discredit Amulek's spiritual credentials by having him appear to be blasphemous. In this case, to decide that the Atoning Messiah won't atone.
Of course the key to this issue is the idea that man would be saved "in his sins." It is that phrase with which Amulek has the theological issue, not with the mission of the Atoning Messiah. Amulek makes it clear that salvation cannot occur without a remission of sin. Since no unclean thing can enter into heaven, no man with sin can enter. As Amulek points out, how can one be saved except in the kingdom of heaven? Amulek answers this charge by pointing out that Zeezrom has made an error in his language. Amulek has answered truthfully and with straightforwardness. It is Zeezrom who has muddied the issue.