Here's what we know about Julian of Toledo:
His parents were Jews, but he was raised Christian. He joined the church, became a monk, then an abbot, then finally an archbishop.
Julian eventually became the first bishop to have primacy over the entire Iberian peninsula by, let's say, less than savory means: he assisted in the assassination of the king.
As the big time primate (that is the technical term, right?), Julian of Toledo did everything he could to persecute his former people — changing Catholic laws to further prosecute Jews, reinforcing anti-Semitic activities, and encouraging others in power to do the same.
These actions helped transform Toledo from one one of the most diverse and openly accepting regions in Western Europe into yet another center of hatred and bigotry. In fact, it is arguable that Spain's long history of anti-Semitism, right up through the Inquisition, can be traced right back to Julian's policies.
For all of these transgressions against his own people and, frankly, all of humanity, Julian was doomed to suffer in eternal hellfire to atone for his sins.
Nah, just kidding. They made him a saint.