During the long stretch of Roman peace, the state began to ask for more loyalty than Christians could give. And when they could not, their fellow-citizens began to hate them for their unbending convictions, and even called for their death. Thus, the world hated Christians. Christians, like others at times, are slandered and intentionally mischaracterized. But some people would rather accuse a person falsely or call them bad names or slander them, rather than tell the truth.
Hatred does that.
Our Lord Jesus cared enough for us to prepare us, and to warn us that such would happen. And that helps. If the disciples looked for kindness and gratitude from man they would be painfully disappointed. The must expect to be mistreated like their Master. Jesus is dispatching an army into the world.