The war broke out because other nations had different values and goals. Likewise, there would be no conflict between the Kingdom of God if there were no difference between it and the world. If we had the same pursuit of self-interest and personal gain we would fit right in. But as long as Jesus' Kingdom is different, there will be persecution. However, persecution is not a dismal prospect, for it holds the promise of joy.
Persecution brings rejoicing because it places in the company of the apostles and prophets.
Jesus says that when we are persecuted we are placed in the line-up of the greats. But even better, you will receive a reward for our troubles. You must wait until you get to heaven to receive it, but it is surely there. Furthermore, you should rejoice in persecution because it proves that you are really part of the Kingdom and not an imposter. Persecution is the badge of authenticity.