What should be the most important subject in any school?
The most important subject in the school would be – God! We know that it is His will that His name would be holy throughout the school (Matthew 6:9), and education and training would be in the nurture and admonition of the Lord.
Fathers, do not provoke your children to anger, but bring them up in the discipline and instruction of the Lord (Ephesians 6:4).
Note that He does not even mention math, science, English, or history. Yes, we must study those subjects, but they are to be taught in a way that gives God the glory that He is due.
Also, using His Word as a guide, children would be taught to discern ungodly, anti-Christian teaching and how to think about that topic from God’s point of view.
See to it that no one takes you captive by philosophy and empty deceit, according to human tradition, according to the elemental spirits of the world, and not according to Christ (Col 2:8).
Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect (Romans 12:2).
Your word is a lamp to my feet and a light to my path (Psalm 119:105).
They would be trained not only to protect their minds, but how to take every thought captive to Christ. Thousands of discussions would take place over the course of their educational years that examined the prevailing thoughts of the day and they would be held up to Scripture for analysis.
For the weapons of our warfare are not of the flesh but have divine power to destroy strongholds. We destroy arguments and every lofty opinion raised against the knowledge of God, and take every thought captive to obey Christ (2Co 10:4-5).
There would be prayer before school, before classes, before lunch, when children are going through something difficult, for children to come to faith, and on and on.
There would be chapel. A message would be preached and Christ would be lifted up before the children in prayer, praise, and preaching. Yes, children would come together every week and sing praises to the Lord. Hallelujah!