Saint Junipero Serra - a halo stained with blood?

Visitors view the altar and Father Junipero Serra's resting place inside the Basilica at the Carmel Mission in Carmel, California September 1, 2015. REUTERS/Michael Fiala

VATICAN CITY (Reuters) - Was he a saint or a sinner, an evangelizer or an enslaver?

Next week in Washington, Pope Francis will preside over one of the most controversial acts of his papacy. He will confer sainthood on the 18th century Spanish missionary Friar Junipero Serra, and in doing so, dive into a cultural battle in the United States.