Whether denied by Protestant or by sedevacantist, the answer to that question in matters spiritual (which should pervade our daily lives, public and private) is still: the Pope, the Bishop of Rome, currently Francis, né Jorge Mario Bergoglio.
This applies whether he be liked or disliked. It applies whether he be ascetic or libertine. (All indications are that Pope Francis is the former. For truly horrid anecdotes of the latter, see some of the popes around the turn of the eleventh century, which the Church survived, as She always does, by the grace of the Holy Ghost.) And it applies whether he speak about faith, fables, or football (on only the first of which he can pronounce with infallible authority). It even applies if, in modesty, the Holy Father himself avers, as Pope Francis did early in his reign, that “no one is the most important person in the Church.”
Should we be in doubt, or be asked to explain the Church’s position to a non-Catholic, let us keep the following from the Acts of the Council of Ephesus (ad 431) in mind:
Philip the presbyter and legate of the Apostolic See said: There is no doubt, and in fact it has been known in all ages, that the holy and most blessed Peter, prince (ἔξαρχος) and head of the Apostles, pillar of the faith, and foundation (θεμέλιος) of the Catholic Church, received the keys of the kingdom from our Lord Jesus Christ, the Saviour and Redeemer of the human race, and that to him was given the power of loosing and binding sins: who down even to today and forever both lives and judges in his successors. The holy and most blessed pope [later Saint] Cœlestine, according to due order, is his successor and holds his place, and us he sent to supply his place in this holy synod, which the most humane and Christian Emperors have commanded to assemble, bearing in mind and continually watching over the Catholic faith. For they both have kept and are now keeping intact the apostolic doctrine handed down to them from their most pious and humane grandfathers and fathers of holy memory down to the present time, etc.
Agree or disagree with the Pope, but do either in a spirit of truth in charity, and often (as at the end of the Holy Rosary) pray a Pater, Ave, and Gloria for his protection. The shoes of the fisherman are tough ones to fill.