From the Darwinian p.o.v.: Fitness doesn't mean the unfit should survive. Nature absolves its own inefficiencies.
From the logical / existential p.o.v.: Evidence of an opposite is not proof that one or the other doesn't or can't exist. It does not follow that evidence of hot water means there is no cold water, or that evidence of death means there is no life.
From the ancient p.o.v. there are two principles that are fundamental (they still hold this view that chaos and complexity are complementary universal principles
From the monotheistic p.o.v. evil is not a divine principle; evidence of evil points to other causes. There is also a distinction between moral and nature evil.
And finally, no matter which is preferred, evil still there exists. To be human, we are designed to struggle against it.
Thanks for your very reasonable reply, Cornelis.