Actually, public schools teach direct opposition of Christianity. If I tell students they shouldn't have sex outside of marriage, I'd be told I was enforcing my beliefs on the students, yet when a boy wants to change in a girl's locker room, it's called equality.
I could show students a video of people having sex and that's educational, but if I say "the Bible says" I'm breaking the law and need to stop. If a student walks around the school and brags about how many girls he's been with, it's appropriate for a teacher to applaud him, but the student who walks around proclaiming the gospel of Jesus Christ, he must be stopped, because an evil world will tolerate the rape of women before hearing about Jesus Christ.
There's no such thing as being neutral when it comes to the truth.
He who is not with Me is against Me, and he who does not gather with Me scatters abroad. Matthew 12:30

You do the devil's bidding by calling good evil and calling evil good.

Isaiah 5:20 Woe to those who call evil good, and good evil;
Who put darkness for light, and light for darkness;
Who put bitter for sweet, and sweet for bitter!
21 Woe to those who are wise in their own eyes,
And prudent in their own sight!

I have to agree, that by teaching Christianity, he's violating the law, but when the law goes against the world's sin, they change the law and celebrate breaking it. How many principals are there who drive drunk, use illegal drugs, etc.

Fact is Christians take consequences for what we believe, chaplains being discharged, a local college student being expelled for his Christian beliefs not fitting those of his college's counseling program, no refund, nothing. Pastors being arrested for public proclamation of the gospel in ur "free" nation.
The cost of following Christ is high, but consider the even greater cost of going against Him.

The wicked shall be turned into hell,
And all the nations that forget God. Psalm 9:17

Psalm 7:10 My defense is of God,
Who saves the upright in heart.
11 God is a just judge,
And God is angry with the wicked every day.
12 If he does not turn back,
He will sharpen His sword;
He bends His bow and makes it ready.

You're saying there is no right and wrong, it's all subjective, so the principal shouldn't teach Christianity in a school of violence, because you don't like it. So according to your thinking, there's nothing wrong with kids being molested if it fits the general social norms.
Overall, you're saying, I'm a pretty good person Proverbs 20:6 Most men will proclaim each his own goodness,
But who can find a faithful man?
You sound like the average American "I do right by my fellow man, pay my bills, I'm not a bad person" Not intending that in a mocking way, but consider this, you're a criminal in the highest court in the universe. God who is eternally existing Father, Son, and Spirit; created all the universe, not out of necessity, but His good pleasure to do so. In the grand scheme of all the universe,the planet earth is but a speck, you exist as a speck on a speck and insult the God who created and sustains your life. You've violated every law He's gave. You've done evil while ignoring conscious and calling it good.
Consider
Surely You set them in slippery places;
You cast them down to destruction.
19 Oh, how they are brought to desolation, as in a moment!
They are utterly consumed with terrors.
Deuteronomy 32:35 Vengeance is Mine, and recompense;
Their foot shall slip in due time;
For the day of their calamity is at hand,
And the things to come hasten upon them.

Why, so much anger, you have no idea what the Bible says, you just know you hate God. You are arrogant in your unbelief. You love your sin and the Bible tells the truth about you. Your heart is full of evil, lust, envy, hatred of good, but what I hear you saying is Hey coach stop worshipping Jesus and serve the sin nature, forsake the truth, return to the darkness, don't you quote that Bible, I don't like it. Because of Christ, I am no longer a slave to sin, no longer blinded to the truth, no longer addicted to porn. I couldn't go back to the world even if God said I wouldn't be judged for it.

Christ has redeemed us from the curse of the law, having become a curse for us (for it is written, “Cursed is everyone who hangs on a tree”Galatians 3:13

Galatians 1:11 But I make known to you, brethren, that the gospel which was preached by me is not according to man. 12 For I neither received it from man, nor was I taught it, but it came through the revelation of Jesus Christ.

13 For you have heard of my former conduct in Judaism, how I persecuted the church of God beyond measure and tried to destroy it. 14 And I advanced in Judaism beyond many of my contemporaries in my own nation, being more exceedingly zealous for the traditions of my fathers.

15 But when it pleased God, who separated me from my mother’s womb and called me through His grace, 16 to reveal His Son in me, that I might preach Him among the Gentiles, I did not immediately confer with flesh and blood,

Answer me this question, is it wrong to murder? How do you determine your answer?

God has perfect knowledge of all things, but unlike your neighborhood church throwing Super Bowl parties to impress your carnal mind, God converts sinners, giving them a new nature as He has mercy on whom He wills and whom He wills, He hardens.

Romans 9:13 As it is written, Jacob have I loved, but Esau have I hated.

In real life, the empty tomb is there, the place where the temple stood that Jesus said would be destroyed. The Bible says in the last days there will be mockers, men will be lovers of themselves, etc. Those who desire to live godly lives are persecuted in some way, evil men and imposters grow worse and worse.
Research how the apostles died, tell me what you find prior to your next foolish statement, tell me if you'd endure that to defend your atheism.

Yes, I could see how that would be the conclusion of someone who's never read the Bible. Your willfull ignorance doesn't excuse the fact that you will stand before the Lord Jesus Christ, but you assume that by mocking and denying the truth, it goes away.
Jesus said "Heaven and earth will pass away, but my words never will" Consider how many revisions the average textbook goes through, yet the Bible's truth is unchanging. Every prophesy has been fulfilled exactly as prophesied, the apostles suffered immense persecution as Jesus said they would. Believers today suffer immense persecution and testify of being radically transformed by the power of the gospel.
I bear personal testimony of the gospel's transforming power. I was full of cursing and bitterness, envy, and perverted lust, but God has transformed me and though I am not perfectly sinless, nor will I be in this lifetime, I thank God that He's redeemed me from the depths of my sinfulness, so the idea of the Bible being fiction is completely foolish. You mock a holy God and praise a beverage brand, while cursing the God who gave and sustains your life. Repent and believe on Jesus Christ.

You can hate the truth, that doesn't change it, fact is God, who is infinitely holy commands all men everywhere to repent. You're a slave to sin and serve the desires of your master, the devil, as I once did, but have been set free by the power of Jesus Christ, who took on flesh and endured the wrath of God on behalf of sinners. You hate a man for proclaiming that truth and defend those who encourage human sacrifice to their false gods (I'm almost certain, you can't deny this)
As it is written:
There is none righteous, no, not one; There is none who understands; There is none who seeks after God.
They have all turned aside; They have together become unprofitable; There is none who does good, no, not one.
Their throat is an open tomb; With their tongues they have practiced deceit; The poison of asps is under their lips
Whose mouth is full of cursing and bitterness
Their feet are swift to shed blood;
Destruction and misery are in their ways;
And the way of peace they have not known.
There is no fear of God before their eyes. Romans 3:10-18

You are condemned and awaiting judgement, I assure you it is a fearful thing to fall into the hands of the living God.

Whoever believes in Him is not condemned, but whoever does not believe is condemned already because he has not believed in the name of the only begotten Son of God.
And this is the condemnation, that the light has come into the world, and men loved darkness rather than light, because their deeds were evil.
For everyone practicing evil hates the light and does not come to the light, lest his deeds should be exposed. John 3:18-20

Your god is the god of this evil age, not the one true god, it's obvious that you're faithful to him, but I warn you, he'll be cast into the lake of fire at the judgement throne of Jesus Christ, along with everyone not written in the book of life. Repent of your sins and turn to Christ, the one who has the power to cast body and soul into hell, whom you've mocked your entire life, in spite of the fact that He's given you life and can take it away in an instant. Before you say "oh you're trying to scare me into believing", consider the fact that false converts will be cast into the lake of fire, many of whom go to church and appear to be godly. So unless you be converted, you will suffer the wrath of God that abides on you currently.
Jesus Christ, the sinless Son of God took on human flesh, was born into the world He had made of a virgin in a stinking stable, was despised and rejected by those who claim to serve God. He performed miracles, clearly seen by multitudes of healing, casting out demons, raising the dead. He was betrayed by one of His disciples, suffered the wrath of God at the hands of sinners and rose from the grave to be the mediator for all who will believe on Him. Why couldn't God just forgive people without Christ's suffering?, because that would make God unjust. Because God is good, He must punish every bit of evil. Because God is eternal, the offense is greater. If a boy lies to his teacher, he gets a 0, he lies to his parents, he gets grounded, lies to police, he gets arrested, but all sin is against an infinitely holy God. There's no neutral ground with God, you're either a savant of God having been saved by grace through faith in Jesus Christ, or His enemy.

Romans 5:8 But God demonstrates His love for us in that while we were still sinners, Christ died for us.
Christ died for the ungodly that would later repent and believe on Him and one is saved by trusting Him alone, not "good" deeds, not reforming one's behavior, not repeating a prayer, not being baptized, no by faith alone in Jesus Christ. I suggest you start with reading the Bible. By mocking Christianity on a Christian site, you waste your life, which is as a vapor in comparison to eternity. I speak as one raised on the religion of the age along with some Christian teaching, who held to being a Christian and repeated tons of prayers, but God saved this religionists out of his sin, out of his bondage to pornography, I don't say that as a sob story, but as praise to the all powerful God, who is gracious to whomever He wills to be, not because of my so-called good deeds, but in spite of them. To God alone be the glory and He will be glorified in either saving you for Himself or casting you into the lake of fire. If you could but get a glimpse of His infinite worth and how you a finite creature have insulted Him. Repent and trust the Lord Jesus Christ. Have no confidence in yourself. You must be born again, by the sovereign grace of our Lord Jesis Christ.

This man is violating his role as a principal, doesn't he know there's a separation between church and state? Or maybe, he recognizes that God is sovereign and we ought to obey Him rather than men.