Pope Francis and Patriarch Kirill of the Russian Orthodox Church held a momentous meeting on Friday, and used the opportunity to condemn same-sex marriage.
The meeting, which marked the first time leaders from the Catholic and Orthodox churches have met in nearly 1,000 years, took place in Cuba, and the Vatican issued a joint statement from the two religious leaders.
"The family is the natural centre of human life and society. We are concerned about the crisis in the family in many countries.
The family is based on marriage, an act of freely given and faithful love between a man and a woman. It is love that seals their union and teaches them to accept one another as a gift. Marriage is a school of love and faithfulness.
We regret that other forms of cohabitation have been placed on the same level as this union, while the concept, consecrated in the biblical tradition, of paternity and maternity as the distinct vocation of man and woman in marriage is being banished from the public conscience."
Pope Francis has been praised in the past for his progressive views on LGBT issues, especially in comparison to past heads of the Catholic Church, but he has still denounced same-sex marriage several times.
Patriarch Kirill has strongly been against LGBT rights, even calling the legalization of same-sex marriage "a very dangerous sign of the apocalypse."