The teaching passage begins with the true name, then highlights the essence to which that name is tied, which is the gospel.
The Savior explains that if the essence, or the gospel, is not Christ’s gospel, then the men who become called by that name will not be called into God’s presence, but rather into the fires that destroy the wicked at the end.
The teaching ends with the reiteration that the true gospel has been delivered. Therefore the true gospel may have the true name of Christ. The apostles represent both the name and the essence.