All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
We advise you not to enroll your son in such schools since his creed and religion will be at risk because Christians are keen to implant their beliefs and rites in our children's minds. Christians are also desirous to infuse our children's minds with doubts and misconceptions. So, it is safer and better to be ignorant than to be a non-Muslim and die as such.
The Prophet said: “Every child is born on the Fitrah (natural disposition upon which Allah created mankind). His parents may make him/her a Jew, a Christian or a Maji.” [Al-Bukhari and Muslim]
It is every father's duty to help his children learn their religion and to teach them religious knowledge and not other sciences, especially if there is possible danger on their behavior and faith.
It is your duty to bring Muslim specialized tutors to teach your son at home, and you can discuss such a question with Muslim schools and ask them to establish some classes for the disabled to save them from the traps of the Christians.
For more benefit on the danger of residing in non-Muslim countries on raising children, please refer to Fatwa 179175.
For more benefit on Muslims living in non-Muslim countries, please refer to Fataawa 81142, 86405, 88291, 377986, 81642, 369667, 81464 and 89879.
We ask Allah to bless you and your son, make matters easy for you, and heal your son from every disease.
Allah knows best.