How does Bigger treat the reverend when he comes to his jail cell? Why would he treat the reverend this way?

The Reverend urges Bigger to "turn to Jesus!" and in his rambling sermon, Hammond hopes to offer Bigger some hope of salvation and heaven, for he will surely be executed and in not very much time. Bigger resists the Reverend's invitation to salvation and after becoming frustrated with Bigger's obstinate antics, the Reverend intends to leave the boy, but not before setting a wooden cross necklace around Bigger's neck. Bigger threatens the Reverened because he feels that he has lost all hope, even for a Christian salvation.