Pope Pius IV appointed him as his secret representative for Northern Europe with the mission to reconstruct the Catholic Church in Denmark and Sweden, which he did it.
Christina was the granddaughter of Gustav Vasa, the same who started Lutheran reform against the Catholic Church in Sweden and part of Denmark.
Pimentel and others aimed to convert the Swedish Queen Christina, who created in his honour the Amarant Order, a cultural organization still existing.
As a poet, he shows a personal tone, due to his military and diplomatic obligations, out of Spain and its literary tendencies.
He wrote, too, Selvas dánicas, (Copenhagen, Pedro Morsingio, 1655), a poetical genealogy of the Royal House of Denmark, and dedicated to Queen Sophie Amalie of Brunswick-Lüneburg; Selva militar y política, (Cologne, Antonio Kinchio, 1652), dedicated to King of the Romans Ferdinand IV of Germany; La constancia victoriosa, égloga sacra, (Cologne, Antonio Kinchio, 1655), which is a translation of the Book of Job, and is dedicated to Queen Christina of Sweden, etc.