Tenant could have been any religion as far as we know now. If Muslim, and he did it, it may have nothing to do with religion, or if it did it could be in the sectarian Northern Ireland type of animosities rather than some grand jihadist, Islamist, whatever inspiration.
Could just be nuts.
Do you hear the dogs barking? -- Conan Doyle
Shermy--not a muslim. Ex-con Edward McDonald. Sounds Irish Catholic to me.