They say that he is not allowed at school or school activities. He has not been able to go to school for 2 weeks. Every Friday during lent our school won't serve meat because the Christians can't eat it, but we get a choice of a salad or yogurt instead of the main meal. This question is hard to answer without more information.
Many private schools are religion-based and it is part of the curriculcum.
For now, I'll assume it is a public school. They can neither prefer one religion over another, nor can they prefer non-religion over religion. The bottom line is our State Constitution guarantees the freedom of worship and belief. In so doing, it demands absolute neutrality in the treatment of religious groups. The information contained in this site is made available as a public service to the general public and is not intended to serve as legal advice.