What is the role of the Holy Spirit in the Roman Catholic church? When I search online, I mostly find stuff about filioque. But I want to know specifically what he does. What is his role? How does he affect our salvation?
The theology of the Holy Spirit (or Holy Ghost - the two terms mean the same thing) is a huge subject. This article gives a systematic explanation from the Catholic point of view.
Catholic theology of the Holy Spirit is very little different from general Protestant or Orthodox theology of the Holy Spirit, with a few notable exceptions, which I will attempt to list:
There may be others that I am unaware of.