"Niceness" - wholesome, integrated personality - is an excellent thing. We must try by every medical, educational, economic and political means in our power, to produce a world where as many people as possible grow up "nice;" just as we must try to produce a world where all have plenty to eat. But we must not suppose that even if we succeeded in making everyone nice we should have saved their souls. A world of nice people, content in their own niceness, looking no further, turned away from God, would be just as desperately in need of salvation as a miserable world - and might even be more difficult to save.
For mere improvement is not redemption, though redemption always improves people even here and now and will, in the end, improve them to a degree we cannot yet imagine.
God became man to turn creatures into sons: not simply to produce better men of the old kind but to produce a new kind of man. It is not like teaching a horse to jump better and better but like turning a horse into a winged creature.
- C.S. Lewis, Mere Christianity