"The point" of Dante's journey is to save his soul from a fate similar to those that Dante pilgrim witnesses in hell. The journey is supposed to prove what Christians would have been taught on earth: that this life and its decisions have to do with the afterlife. Dante solidifies this fact by including famous people in the Divine Comedy. For instance, Dante names two Popes in hell: Nicholas III and Boniface, both condemned for simony. By alluding to real people, Dante poet creates an even more dramatic scene, from which Dante pilgrim does not want to stay, and which Dante poet hopes will convince his readers to live an upright, Christian lifestyle.
The point of Dante's journey through the after-life is to express his own living hell after his exile from Florence and, at the same time, enlighten and edify his readers concerning what it truly means to be an upright Christian. Quite frankly in Dante's time to be a Christian meant listening to the Pope unquestioningly. This infuriated Dante since he at a young age entered the political scene of Florence at a time when Florence was more important than Rome for the economical and political growth and stability of the Italian peninsula. Dante knew the true faces of these religious figures.
In fact Dante was seen as such a threat that he was very nearly excommunicated. The Church initiated an investigation against him in which he made his own defense beautifully in such terms that even the Church had to admit that he was undoubtedly Christian through and through. Still, the Church banished some of his works that touched on political subjects for fear of what they might stir, pretty much proving what Dante says about them in the Divine Comedy.
Likewise I love to rip on our political system and the blatant corruption of our government in my book _White Man's Inferno_. Because Dante proved a true poet has to tell it how it is with no candy coating!