If you don't believe Jesus Christ is our Lord then how can you claim Catholicism is a Christianity? I, of course, don't think it is....but I'm wondering why you think Catholics are Christians if they believe they need a priest so as not to go to hell, instead of Jesus?
1) Because Catholicis is the main branch of Christianity with 1.2B at least number of members
https://en.wikipedia.org/wiki/List_of_Christian_denominations_by_number_of_members2) Because as italian you are raised as Catholic (although the italian constitution sanctions the complete independent between the Italian territory and the the Holy See territory)
3) Because Catholicis is the real Christianity
4) Because I like to follow traditions
Thank You
PS: Wikipedia link is the best link I can find at the moment for number of Christianity members. I will post others sources as soon as I'll find a more independent source to post.