In light of the historic legislation passed by the Supreme Court (yes, I know this isn't the Court's role, but it accurately describes the effect of their decision), legalizing same-sex marriage, I thought revisiting prophetic words from Francis Schaeffer would be enlightening. Below is an excerpt from a lecture Schaeffer gave in 1982, and also part of his "Christian Manifesto" published the same year.
Schaeffer displays what happens when a society replaces Christian truth (which is actual truth) with humanism. Remember, this was written over thirty years ago, at a time when it seemed "conservatism" was on the upswing. As Schaeffer was fond of saying, conservative humanism is no better than liberal humanism.
So, Humanism is the absolute certain result, if we choose this other final reality (instead of Christianity) and say that is what it is. You must realize that when we speak of man being the measure of all things under the Humanist label, the first thing is that man has only knowledge from himself. That he, being finite, limited, very faulty in his observation of many things, yet nevertheless, has no possible source of knowledge except what man, beginning from himself, can find out from his own observation. Specifically, in this view, there is no place for any knowledge from God.
But it is not only that man must start from himself in the area of knowledge and learning, but any value system must come arbitrarily from man himself by arbitrary choice. More frightening still, in our country, at our own moment of history, is the fact that any basis of law then becomes arbitrary -- merely certain people making decisions as to what is for the good of society at the given moment.
Now this is the real reason for the breakdown in morals in our country. It's the real reason for the breakdown in values in our country, and it is the reason that our Supreme Court now functions so thoroughly upon the fact of arbitrary law. They have no basis for law that is fixed, therefore, like the young person who decides to live hedonistically upon their own chosen arbitrary values, society is now doing the same thing legally. Certain few people come together and decide what they arbitrarily believe is for the good of society at the given moment, and that becomes law.
Now, compare what Schaeffer said to what Romans 1 describes:
Romans 1: For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who by their unrighteousness suppress the truth.  For what can be known about God is plain to them, because God has shown it to them.  For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse.  For although they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened.  Claiming to be wise, they became fools,  and exchanged the glory of the immortal God for images resembling mortal man and birds and animals and creeping things.  Therefore God gave them up in the lusts of their hearts to impurity, to the dishonoring of their bodies among themselves,  because they exchanged the truth about God for a lie and worshiped and served the creature rather than the Creator, who is blessed forever! Amen.  For this reason God gave them up to dishonorable passions. For their women exchanged natural relations for those that are contrary to nature;  and the men likewise gave up natural relations with women and were consumed with passion for one another, men committing shameless acts with men and receiving in themselves the due penalty for their error.  And since they did not see fit to acknowledge God, God gave them up to a debased mind to do what ought not to be done.