Benjamin declared that there was no other name through which salvation would come. After describing the need for repentance in order to access the atonement, he declares that there is no other means by which salvation comes. Not only no other being, but no other method. This is the only way in which humankind can be reconciled to Jehovah and the covenant.
The reason that this statement leads directly to the command “believe in God; believe that he is, and that he created all things,” is because the name through which salvation is to come identifies the mortal mission of Jehovah on earth. There is a direct correlation. Nephite understanding was that Jehovah was their God, and that Jehovah himself would come to earth as the mortal who history will know as Jesus.
Thus, after commanding that they believe in God, or Jehovah, Benjamin reemphasizes that they “must repent of your sins and forsake them, and humble yourselves before God.” These are the actions that they must take to make the atoning Messiah’s mission applicable to their own lives.