The world is a realm of wrongdoing, and the devil is lord over it. Those who do not believe are citizens of the world, submit to its rule, and, together with the world, are in the power of the evil one.
But those who believe tear themselves away from the world and the realm of wickedness and are gathered into the realm of faith and salvation.
Therefore a Christian should trust no one; but everyone should act as though he were dealing with one who is evil, with a foe and an enemy— should act as though he were dealing with one who is ungrateful, and should expect persecution and the height of ingratitude in return for deeds of kindness.
For what do they pay for our troubles? Nothing else than their desire that we be thrust into hell and be afflicted with evils of every kind. For the greatest deeds of kindness they return the greatest deeds of wickedness. Accordingly, this passage pertains to patience. — Martin Luther (on 1 John 5:19).