"We need to be very conscious that evil is not some nameless, impersonal and deterministic force at work in the world. Evil, the devil, works in and through human freedom, through the use of our freedom. It seeks an ally in man. Evil needs man in order to act. Having broken the first commandment, love of God, it then goes on to distort the second, love of neighbour. Love of neighbour disappears, yielding to falsehood, envy, hatred and death. But it is possible for us not to be overcome by evil but to overcome evil with good (cf. Rom 12:21). It is to this conversion of heart that we are called. Without it, all our coveted human “liberations” prove disappointing, for they are curtailed by our human narrowness, harshness, intolerance, favouritism and desire for revenge".
The full text may be read here.