It is well known that Nicholas was harsh with his own Church, trying to make it come back to its old ways. However, looking at his actual statements makes him appear much harsher than one might originally think. For example, in a response he wrote to the Catholic bishops of Lorraine, Pope Nicholas said:
“You affirm that you are submissive to your sovereign, in order to obey the words of the apostle Peter, who said, ‘Be subject to the prince, because he is above all mortals in this world.’ But you appear to forget that we, as the vicar of Christ, have the right to judge all men: thus, before obeying kings, you owe obedience to us; and if we declare a monarch guilty, you should reject him from your communion until we pardon him...
We alone have the power to bind and to loose, to absolve Nero and to condemn him; and Christians can not, under penalty of excommunication, execute other judgment than ours, which alone is infallible. People are not the judges of their princes; they should obey without murmuring the most iniquitous orders; they should bow their foreheads under the chastisements which it pleases kings to inflict on them, for a sovereign can violate the fundamental laws of the State, and seize upon the wealth of the citizen, by imposts or by confiscations; he can even dispose of their lives, without any of his subjects having the right to address to him simple remonstrances. But if we declare a king heretical and sacrilegious, if we drive him from the Church, clergy and laity, whatever their rank, are freed from their oaths of fidelity, and may revolt against his power.”
Trying to incite Charles the Bald to invade the King of Lorraine, Nicholas wrote:
“We order you, in the name of religion, to invade his states, burn his cities, and massacre his people, whom we render responsible for the resistance of their bad prince.”
Finally, to an envoy from Constantinople, Pope Saint Nicholas the First wrote:
“Fear, then, our wrath and the thunders of our vengeance, for Jesus Christ has appointed us with his own mouth absolute judges of all men, and kings themselves are submitted to our authority...
I glorify you for having maintained your authority by putting to death those wandering sheep who refuse to enter the fold, and you not only have not sinned by showing a holy rigor, but I even congratulate you upon having opened the kingdom of heaven to the people submitted to your rule. A king need not fear to command massacres, when these will retain his subjects in obedience, or cause them to submit to the faith of Christ, and God will reward him in this world, and in eternal life, for these murders...
It is evident that the popes can neither be bound nor unbound by any earthly power, nor even by that of the apostle, if he should return upon the earth, since Constantine the Great has recognized the pontiffs held the place of God upon earth, the divinity not being able to be judged by any living man. We are, then, infallible, and whatsoever may be our acts, we are not accountable for them but to ourselves.”