Popes are an interesting lot and John is no different. He was a man caught between two worlds; not just the world of politics and the world of Faith, but within each of those worlds as well. He practiced intolerance early in his career, supporting the anti-pope and yet was forgiven and eventually elected Pope.
In the West Theodoric the Ostrogoth was an Arian, while many of his subjects were orthodox Catholic. In the East, Justin was Orthodox while many of his subjects were Arian. In the West they looked to the East; in the East to the West. In the East the Arians appealed to Theodoric for help and Theodoric sent John to appeal for justice from the persecution. He was received in honor and argued from love for those who believed something that he did not and Justin relented, with some minor caveats. Theodoric was more political and viewed his non-Arian subjects with suspicion as possibly more loyal to the East. John's success and warm welcome in the East also raised his suspicions. Ironically, the love that John proclaimed brought relief in the East but persecution and his death in the West. His life and martyrdom are an example of the merits and perils of tolerance.
When a few days had passed, King Agrippa and Bernice arrived in Caesarea on a visit to Festus. Since they spent several days there, Festus referred Paul’s case to the king, saying, “There is a man here left in custody by Felix. When I was in Jerusalem the chief priests and the elders of the Jews brought charges against him and demanded his condemnation. I answered them that it was not Roman practice to hand over an accused person before he has faced his accusers and had the opportunity to defend himself against their charge. So when (they) came together here, I made no delay; the next day I took my seat on the tribunal and ordered the man to be brought in. His accusers stood around him, but did not charge him with any of the crimes I suspected. Instead they had some issues with him about their own religion and about a certain Jesus who had died but who Paul claimed was alive. Since I was at a loss how to investigate this controversy, I asked if he were willing to go to Jerusalem and there stand trial on these charges. And when Paul appealed that he be held in custody for the Emperor’s decision, I ordered him held until I could send him to Caesar.”
-- Acts 25:13-21