Gandolf: wears a white robe, leads the people, custodian of tradition, carries a staff, probable summer residence in Gandolf Castle (Castel Gandolfo)=THE POPE
No, the Pope was definitely Gollum.
Gandalf was raised from the dead or the depths of hell though and can act directly with immense power against the evil supernatural forces which is more Godlike or Angelic. Could be Pope but then where are the bishops, priests and the structure of the church? I think Tolkien may have intentionally left the church as an overt entity out of his world in order to keep the book open to all rather than purely sectarian.