"Today, as Christians, all of us are called to put behind us all prejudice toward the faith that others profess with a different emphasis or language, to offer one another forgiveness for the sins committed by those who have gone before us, and together to implore from God the gift of reconciliation and unity," he said.

The Pope spoke March 31 to about 150 people taking part in an international congress organized by the Pontifical Committee for Historical Sciences. The congress, held March 29-31, discussed the theme, "Luther: 500 Years Later. A Rereading of the Lutheran Reformation in the Historical, Ecclesial Context."

The Pope told the participants that his first reaction to hearing about "this praiseworthy initiative" was one of gratitude to God and "a certain surprise, since not long ago a meeting like this would have been unthinkable."

"Catholics and Lutherans together, discussing Luther, at a meeting organized by an office of the Holy See – truly we are experiencing the results of the working of the Holy Spirit, who overcomes every obstacle and turns conflicts into occasions for growth in communion," he said.

Pope Francis said he was pleased the commemoration of the 500th anniversary of the Reformation offered this occasion to jointly study such past events.

"Serious research into the figure of Luther and his critique of the church of his time and the papacy certainly contributes to overcoming the atmosphere of mutual distrust and rivalry that for all too long marked relations between Catholics and Protestants," he said.

"An attentive and rigorous study, free of prejudice and polemics, enables the churches, now in dialogue, to discern and receive all that was positive and legitimate in the Reformation, while distancing themselves from errors, extremes and failures, and acknowledging the sins that led to the division," the Pope said.

While the past cannot be changed, he said, 50 years of dialogue means there can be "a purification of memory," which is "to tell that history differently," in a way that is "free of any lingering trace of the resentment over past injuries that has distorted our view of one another."