He persecuted those who refused to honor him as God. He banished John to Patmos. When John wrote the book of Revelation, the church was under savage persecution. Satan meant to destroy the church, and Domitian was his tool. Justice will come one day, and the faithful will be rewarded.
Physical life is temporary.
Perseverance is the key to final victory. He expects us to stand firm and never give up. Victory for the faithful and true is inevitable. It will come. We must be loyal.