Naturalism is the underpinning of Secular Humanism. Humanism, as a philosophy that values human beings, is not inconsistent with Christian beliefs and the Bible, as God placed so much emphasis on human beings that He created us in His own image. So it is not the word “humanist” that is so much of the problem, it is the “secular” part, which means to be absent of a God or Supreme Being. Put them together and you have the first problem with Secular Humanism: It’s all about “me”. In other words, God has been replaced by man as the supreme. Thus, the result of putting man in charge of whatever makes him happy is the abandonment of an absolute moral law. Morality is whatever pleases us, whatever may be “politically correct”, and sounds and looks good to other people.
To recognize there is an absolute moral law would require one to acknowledge there is an absolute moral law GIVER: God. Since naturalists, and thus secular humanists do not believe in the existence of God, then there is not absolute moral law giver except man, and we tend to easily accept whatever “feels” good to us. Many may remember the saying that was popularized in the late 1960’s and 1970’s: “If it feels good… do it.” That pretty much sums up man’s moral law philosophy. However, societal trends in political correctness, such as compassion, diversity, human rights and freedoms, etc. also have a strong impact on what the world considers as “moral”, but there is inherent conflicts even among the “politically correct” regarding its finer points. There is probably no better illustration than in the movement to “empower” women to choose to have abortions, and the “rights” of the unborn babies. By definition, if man were indeed the absolute moral law giver, there would be neither conflict nor changes in moral standards to meet the personal desires of various groups. However, since even secular, naturalist, humanist mankind cannot successfully navigate to an absolute standard, it becomes evident, at least to those with a Christian worldview, that man cannot be the giver of absolute morals or truth.