Pope Francis on Sunday defended the Roman Catholic Church's views on marriage as he opened a synod on the family.

The Synod of Bishops is a three-week assembly of bishops from around the world that will look at issues facing Catholic families.

“This is God's dream for his beloved creation, to see it fulfilled in the loving union between a man and a woman,” the pope said. “Rejoicing their shared journey, fruitful in their mutual gift of self.”

“God wants us to carry out the church's mission in truth, which is not changed by passing fads or popular opinions.”

On the eve of the synod, a Polish priest who served with the Vatican's doctrinal arm announced he's gay and has a partner.

Monsignor Krysztof Olaf Charamsa called on the Holly Father to revise the Catholic teaching on homosexuality, which states that all people should be respected but that gay sex is “intrinsically disordered.”

With his partner Eduardo by his side, Charamsa called on the church to “open your eyes to the suffering of gay people, to their desire for love.”

In a statement, the Vatican called the priest's actions “irresponsible” and suggested that his service as a theologian at the Vatican was over.