It is true that the New Testamant is large made up of letters from Paul, but then again, you have to consider that Christians believe that Paul was following Jesus' message and shaping the "Christian" practices through Divine guidance

 

Based on whose authority? Where in the bible or any revelation is it said that paul was given authority by jesus or God to be a prophet or missionary of God? So if you make that authority without proof or revelation then by default one has made Pauls writing before jesus.

 

Saying Paul is more important than Jesus is like saying the so-called scholars in Islam are more important that our Prophet (saw).

 

The difference is that Paul incorporated his own creed and experiences as part of revelation.  Whereas the scholars of Islam base their writings on the words of the Prophet SAW and the Quran. And within Islam scholars are allowed to be scrutinized based on these two foundations.  However,  pauls writing are revelations and are not based on Jesus's testimony but rather his own experiences and beliefs (including dreams) and therefore THE foundation within modern day christianity. 

which makes pauls writings more important to modern christian belief than jesus's.