If he loves the world so much, then why does God allow disasters, famine, disease, slavery, suffering, etc?
To quote Epicurus and Hume: "Is God willing to prevent evil, but not able? Then he is impotent. Is he able, but not willing? Then he is malevolent. Is he both able and willing? Whence then is evil? Is he neither able nor willing? Then why call him God?"
Those are a consequence of what Adam and Eve did. The whole creation degenerated. We, their descendants, and the animal and plant life must endure the consequences of "natural evil."
The vast majority of evil that scandalizes us, however, is what humans do to each other. And you can't blame God for that, no matter how much you try.
Why God permits evil to exist? Because without it there would be no faith. If He were to destroy evil immediately there would be no basis for faith, it would be all about knowledge and fear.