God is a God of law and order. He created all the laws: mathematical law, the law of gravity, even the laws of our country which derived from the ten commandments. The top scientists and mathematicians are all very godly people. Even the one who created the first calculator, and how it links to the computer and now to AI. Watch more about it here: https://youtu.be/XGUuaUzDhII?si=z0gJtXHho1idbVyN
Tell him stories of standing up for his faith, of martyrs in the past and in the New Testament. And the verses: if you deny me before men, I will deny you. And "take up your cross and follow me" and "he who has lost houses, or mothers or brothers for my sake". All these are important lessons -- more important than English or Math, because their eternal lives depend on it. Also, if after all that, he is feeling ashamed, remind him of how Jesus still accepted Peter after Peter denied him 3 times, asking him to feed His lambs and sheep. There's still hope.