Jesus’ mission is clearly spelled out in Mark 8:31. His work as the Anointed One was to suffer, die, and rise from the dead. His suffering and death was necessary to pay the penalty for sin. He had had to suffer and die so that those who believe in him can be forgiven by God. His resurrection was also necessary, as proof that death has been defeated, and that God has the power to raise our mortal bodies from the grave.
31 And he began to teach them that the Son of Man must suffer many things and be rejected by the elders and the chief priests and the scribes and be killed, and after three days rise again.