ROME — God wants people to live their vocation in a spirit of strength, Pope Francis told the Vatican gendarme corps, the police force of the tiny city-state.

Revive, guard and “take charge of the gift you have been given, take charge of your vocation … not with a spirit of cowardice, not with the spirit that brings you down, no, with a spirit of faith, love and strength,” the pope said in his homily.

In addition to the more colorful Swiss Guard, the Vatican’s own police force of about 130 men is responsible for papal security, crowd control in St. Peter’s Square and safety, law and order within the Vatican.

To help celebrate the Vatican security service’s patron saint, St. Michael the archangel, the pope celebrated Mass for security personnel at the grotto of Our Lady of Lourdes in the Vatican Gardens. While the feast of the archangels Michael, Gabriel and Raphael was Sept. 29, the Mass with the pope was Oct. 1.

The pope told his own “guardian angels” to revive the flame and rekindle the dream and desire of their vocation.

“Almost all of you,” he said, “entered the gendarme because of a vocation, a desire to do something good, as service, as growth. And then, as it happens to us priests, too, to everyone, one gets used to it; and when one gets used to it, instead of growing, you sink down further and further.”

“If you don’t revive your vocation, if you don’t make it grow every day,” he said, “that vocation of service, which is very beautiful, eventually — this is not a curse, no, it happens to everybody — eventually the things that don’t grow become corrupted” and one can become “lukewarm.”

But, Pope Francis said, loving the service they offer each day is difficult with jobs like theirs, where there is “impatience, anger over something that is wrong, injustices that are apparent and cannot be fixed … this can extinguish charity, and it gives us that spirit of cowardice.”

The pope invited them to always be renewed, to try to be better every day, “to take a step forward in one’s vocation to which we have been called.”