1. Firstly, the spouse of an Irish citizen has a right to live with them in Ireland should they so wish. Accordingly, your husband has now got two options. Firstly, he can judicially review the current refusal to allow him come and live with you in Ireland. he should take this option if you are correct in that all relevant documentation was correctly submitted with his application and there is no error in the application. Secondly, he can submit a fresh application this time with all the documentation correctly submitted and take legal proceedings if this is rejected. However, if his application can be shown to have been refused because he is a Muslim, then this is grounds for it being allowed. There are many Muslims living in Ireland who have visas, so I very much doubt this alleged bias has anything go to do with the refusal of a visa.
2. Additionally, it is unlikely that you being on disability is the basis for the refusal. The ability of a spouse to live in Ireland is not dependent upon finance. A spouse is allowed to live with their Irish spouse in Ireland irrespective of financial circumstances. Finally, because insufficient documentation has been given as the refusal reason, I would tell your husband to go back and apply again. This time including all documentation requested.