"Your courage should inspire every Catholic to a similar fidelity, and to the mutual, prayerful support that helps sustain the integrity of love," Weigel continued.
Weigel, who wrote the definitive biography of Pope St. John Paul II in 1999, noted that the "licentious" current culture can make living a chaste life difficult for anyone.
"Against fierce cultural and social pressures, you strive-with the help of grace, your pastors, and each other-to live the Catholic ethic of human love even as you experience same-sex attractions. Your efforts at fidelity bespeak deep faith, a powerful hope, and authentic love," Weigel wrote.
Weigel's letter was prompted by a recent controversy over a documentary film, "Francesco," which features interviews with Pope Francis and includes a brief section in which, during a discussion of pastoral care of Catholics who identify as LGBT, the pope appears to offer support for civil union laws for same-sex couples.
The Vatican has since clarified that the pope's comments do not pertain to Catholic doctrine regarding the nature of marriage, but to provisions of civil law in the specific context of a 2010 same-sex marriage bill in the Argentine legislature, which Pope Francis, who was then Archbishop of Buenos Aires, opposed. He had proposed the idea of civil unions as a compromise to avoid the legal redefinition of marriage.
Nevertheless, the pope's remarks garnered praise from some Catholics who wish to see a change in the Church's teaching on same-sex marriage, even though Pope Francis has frequently affirmed the doctrinal teaching of the Catholic Church that marriage is a lifelong partnership between one man and one woman.