Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man.
For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil. (Ecclesiastes 12:13-14)
These are the final verses of the Book of Ecclesiastes. Pretty straightforward stuff. I recall using them on the high school graduation diploma I presented to my son during his graduation ceremony in 1996. It is a portion of Scripture that has come up early and often in the course of the home education of my children.
The conclusion of something is a summation statement of all that has come before. At times it can act as the logical progression of a series of propositions. By implication, if one is at the point of hearing a conclusion, one has also heard the introduction and the body of the idea or thesis. So, fearing God and keeping His commandments would imply that the listeners or readers knew God enough to know He is awesome and One to be feared and revered. They would understand that He has likes and dislikes that have been communicated in the form of authoritative directives. Moreover, these statements of His will have everything to do with what is vital for mankind to live successfully; they are possibly the only truly important concepts human beings need to learn and apply. Finally, we are told at the very end that these commandments act as the "yardstick" to measure goodness or wickedness, faithfulness or faithlessness. In other words, there is no mystery in what it takes to please God.
Yet, few Christians make this their starting point in determining the rightness or wrongness of modern day practices. Instead of filtering all ideas and notions through the sieve of God's written Word, they often go along with what the culture promotes without giving the Commandments of God their function of determining right and wrong. For example, what about gender-changing surgeries? What portion of Scripture covers such practices? Why is drug use wrong? Does Scripture address it? Where? What about the process of freezing embryos for future use? Where in Scripture is one given guidance on this? When (if ever) is it appropriate for someone with a devastating and ravishing illness to say, "Enough is enough. It's time for me to die?"
I am not suggesting that the answers come without study and purposeful application of God's Word. Even those of us who have saturated ourselves in the Law of God for decades have hearty discussions that sometimes reveal differences of opinion. But, in those cases, we are arguing (in the good sense) based on common biblical presuppositions. What do those who say we are no longer under God's law argue from? They do have presuppositions and a law base they are drawing from. It just isn't the Bible. In short, many Christians think like humanists and act like humanists because that is the worldview from which they operate.
The Christian homeschooling teacher had better be an expert on biblical law (or strive to be one) in order to impart to his/her students the necessary starting point for them to successfully live out the conclusion of the whole matter. Ultimately, nothing else really matters.