Pope Francis shook up the Catholic world again in late 2015 when he announced the priests would be given the power to absolve the sin of abortion for a “Year of Mercy”.

On November 21, 2016, he extended that power indefinitely in a lengthy Apostolic Letter, entitled Misericordia et misera, (‘Mercy and Misery’).

The church’s stance on abortion did not change, it remains a “grave sin”.

“In the same way, however, I can and must state that there is no sin that God’s mercy cannot reach and wipe away when it finds a repentant heart seeking to be reconciled with the Father,” the letter said.

The decision continued the theme of Francis’ papacy: that the doors of the Church remain open, just as God’s mercy extends to all who repent from sin.

In this picture, Pope Francis exchanges his biretta cup with one received as a gift from a faithful during his weekly general audience at the Paul VI Hall, two days after the letter was published, in Vatican City.