I’ve been learning about the rise of the papacy beginning with Leo IX in the mid 11th century through to Gregory VII. With a child emperor on the throne of the Holy Roman Empire in Henry IV, and the Roman Empire in turmoil after Manzikert, the popes sought and succeeded in raising the power of the papacy. I find their manifesto, so to speak, strikingly similar to what the caliphs had done in the Islamic world in the previous centuries.

Beginning with Leo IX, the popes started building a papal army. Leo fought the Italian normans in 1053 with his. After he lost, his successors joined with the Normans and other Italian knights to create their own standing army. Pope Alexander II and Gregory VII sought and received fealty from sovereign nations. They sought fealty from: Hungary, Norman England, Norman Italy and Sicily, Aragon, Leon and Castile, Poland, etc. It’s really interesting, in the years leading up to the crusades, how the popes tried to emulate the power of the great caliphs and turn Christendom into a sort of Christian caliphate. And it sort of worked, leading to Christendom uniting for the first crusade.

Edit to add the document that brought this thought to my mind. The amazingly brazen Dictatus Papae:

Here is a list of powers Pope Gregory VII of Investiture Controversy fame enumerated in his political manifesto called the Dictatus Papae of 1075, sparking the Controversy:

1 The Roman Church was founded solely by God.

2 Only the Pope can with right be called "Universal".

3 He alone can depose or reinstate bishops.

4 All bishops are below his Legate in council, even if a lower grade, and he can pass sentence of deposition against them.

5 The Pope may depose the absent.

6 Among other things, we ought not to remain in the same house with those excommunicated by him.

7 For him alone is it lawful, according to the needs of the time, to make new laws, to assemble together new congregations, to make an abbey of a canonry, and, on the other hand, to divide a rich bishopric and unite the poor ones.

8 He alone may use the Imperial Insignia.

9 All princes shall kiss the feet of the Pope alone.

10 His name alone shall be spoken in the churches.

11 His title is unique in the world.

12 It may be permitted to him to depose emperors.

13 It may be permitted to him to transfer bishops, if need be.

14 He has the power to ordain the clerk of any parish he wishes.

15 He who is ordained by the Pope may preside over another church, but may not hold a subordinate position. Such a person may not receive a higher clerical grade from any other bishop.

16 No synod shall be called a "General Synod" without his order.

17 No chapter and no book shall be considered canonical without his authority.

18 A sentence passed by him may be retracted by no one. He alone may retract it.

19 He himself may be judged by no one.

20 No one shall dare to condemn any person who appeals to the Apostolic Chair.

21 The more important cases of every church should be referred to the Apostolic See.

22 The Roman Church has never erred. Nor will it err, to all eternity--Scripture being witness.

23 The Roman Pontiff, if he has been canonically ordained, is undoubtedly made holy by the merits of St. Peter, St. Ennodius Bishop of Pavia bearing witness, and many holy fathers agreeing with him. As it is contained in the decrees of Pope St. Symmachus.

24 By his command and consent, it may be lawful for subordinates to bring accusations. He may depose and reinstate bishops without assembling a Synod.

25 He who is not at peace with the Roman Church shall not be considered "catholic".

26 He may absolve subjects from their fealty to wicked men.

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Emphasis added to particularly striking clauses

Essentially, this is a list of powers the caliphs had over the caliphate. Obviously, this is not an apples to apples argument - and the Pope has no claim to descent from Jesus - but as for religio-political powers, this document published by Pope Gregory VII aspires to a papal role not dissimilar to the dual spiritual and political role of the great caliphs.

That’s the way I see it. If you disagree, I’m happy to listen to courteous counterarguments.