What is the difference between Christianity and humanism? It’s easily explained.
Humanists believe in the perfectibility of man by man; and we, as Christians, don’t.
Plato, Rousseau, the modern Left–they all think that if we only get the right science behind it, spend enough money, and apply the requisite measure of brute force, we can solve any human problem. All we need is another law, another set of new regulations, another bureaucracy to put it into play, round up all the dissidents, and bob’s your uncle: Utopia is achieved.
We believe in an ongoing process of individual sanctification, accomplished by God’s grace and by faith in Jesus Christ. We may not reach perfection, but we can get better than we were. As for Utopia, that doesn’t come until Jesus returns and establishes His kingdom on the earth. We do not believe that human nature is just a more complicated form of Play-Doh, to be shaped as desired by anyone clever enough, strong enough, rich enough, or ruthless enough to do it.
But their belief in their own godlike powers, their own wisdom, pretty much explains the whole history of that horrible 20th century. Always breaking eggs to make the perfect omelet, but never getting there no matter how many they break.
See? I told you it was easy.