Taken from page 687 of A Secular Age:

In replacing the low and demeaning picture of human beings as depraved, inveterate sinners, in articulating the potential of human beings for goodness and greatness, humanism has not only given us the courage to act for reform, but also explains why this philanthropic action is so immensely worthwhile. The higher the human potential, the greater the enterprise of realizing it, and the more the carriers of this potential are worthy of our help in achieving it.

But philanthropy and solidarity driven by a lofty humanism, just as that which was driven often by high religious ideals, has a Janus face. On one side, in the abstract, one is inspired to act. But on the other, faced with the immense disappointments of actual human performance, with the myriad ways in which real, concrete human beings fall short of, ignore, parody and betray this magnificent potential, one cannot but experience a growing sense of anger and futility. Are these people really worthy objects of all these efforts? Perhaps in face of all this stupid recalcitrance, it would not be a betrayal of human worth, or one’s self-worth, if one abandoned them. Or perhaps the best that can be done for them is to force them to shape up.

Before the reality of human shortcomings, philanthropy–the love of the human–can gradually come to be invested with contempt, hatred, aggression. The action is broken off, or worse, continues, but informed now with these new feelings, and becomes progressively more coercive and inhumane…

The tragic irony is that the higher the sense of potential, the more grievously real people fall short, and the more severe the turn-around will be which is inspired by the disappointment. A lofty humanism posits high standards of self-worth, and a magnificent goal to strive towards. It inspires enterprises of great moment. But by this very token it encourages force, despotism, tutelage, ultimately contempt, and a certain ruthlessness in shaping refractory human material. Oddly enough, the same horrors which Enlightenment critique picked up in societies and institutions dominated by religion.

…Wherever action for high ideals is not tempered, controlled, ultimately engulfed in an unconditional love of the beneficiaries, this ugly dialectic risks repeating itself.