It is wrong to be sad. Christians cannot be pessimists. Christians must always nourish in their hearts the fullness of joy. Try it, brothers and sisters; I have tried it many times and in the darkest moments, when slander and persecution were at their worst: to unite myself intimately with Christ, my friend, and to feel a comfort that all the joys of the earth do not give – the joy of feeling yourself close to God, even when humans do not understand you. It is the deepest joy the heart can have.
Source: The Violence of Love