Jesus
Jesus has returned to earth after an absence of more than a millennium and a half. His return is never explained, but while here he manages both to raise a child from the dead and to be arrested as a heretic to His own church by the Grand Inquisitor.
The Grand Inquisitor
The Grand Inquisitor is an ancient—well, 90 year old—Roman Catholic Cardinal in charge of interrogating heretics as part of the Spanish Inquisition. He witnesses the resurrection of the child by Jesus and the subsequent worship of Jesus by the crowd. The fear of losing control of the authority of the Church to the figure it allegedly worships prompts the Inquisitor to imprison Jesus and threaten Him with being burned as the ultimate heretic.
Ivan
The Karamazov brother who tells the story of the Grand Inquisitor.
Alyosha
The Karamazov brother to whom Ivan tells the story of the Grand Inquisitor.