Most Christians believe that there are two main ways to respond to evil and suffering in the world:
Christians should pray either that God will remove the causes of evil or that he should help Christians to bear evil and suffering.
If a person has committed a moral evil, eg murder, a Christian would not believe it their place to judge, but they would trust that God would punish the person for his/her action.
Christians should follow Jesus' example in life. This means that they should help those who are suffering, through their actions.
There are teachings which make it clear how Christians should respond to suffering and evil. The parable of the Sheep and the Goats in Matthew 25:31-46, in which Jesus returns to reward all those who have fed the hungry, clothed the naked, visited those in prison, and cared for the sick, teaches Christians to care for those who are suffering.
Jesus' message here is that by ignoring a sick or hungry person, a Christian would be ignoring Jesus himself.
Christians are also taught in the words of the Lord's Prayer to forgive others just as they have been forgiven.