In Genesis chapter 3 we read about what is referred to as The Temptation and Fall of Man. God pronounces a curse on humanity in verses 16-19:
16 To the woman He said:
“I will greatly multiply your sorrow and your conception;
In pain you shall bring forth children;
Your desire shall be for your husband,
And he shall rule over you.”
17 Then to Adam He said, “Because you have heeded the voice of your wife, and have eaten from the tree of which I commanded you, saying, ‘You shall not eat of it’:
“Cursed is the ground for your sake;
In toil you shall eat of it
All the days of your life.
18 Both thorns and thistles it shall bring forth for you,
And you shall eat the herb of the field.
19 In the sweat of your face you shall eat bread
Till you return to the ground,
For out of it you were taken;
For dust you are,
And to dust you shall return.”
These verses explain why evil exists in our world. Human suffering, animal suffering, and natural evil such as earthquakes, were all introduced as a curse from God because of humanity’s sin. Mankind is responsible for its actions, thus bringing the curse upon itself, and man was given dominion over the animals and cosmos, thus bringing the curse upon them. So evil in our world is not a problem for Christianity, rather it is the expected and deserved consequence of human sin.