The first three frames portray the Pope speaking from a pulpit, declaring that his audience has caused a disaster for the church. His audience flippantly apologizes for what they have done. In the third frame the reader finds out that the problem is that there are now only two parts to the trinity. However, in Christian theology, the Holy Trinity is comprised of three persons - the Father, the Son, and the Holy Spirit. Missing from the Pope’s list is the Holy Spirit.
The joke is that the Holy Spirit is sometimes referred to as the Holy Ghost, and, as the reader discovers in the final frame, the Ghostbusters (from the classic 1984 feature film) have destroyed him with their proton packs. This equates the Holy Ghost from the Christian Godhead to an average class 5 free roaming vapor.
