sorry op but you posted this in a topic entitled "am i being unreasonable"
i say yes im afraid you are being. i am not being nasty. but you asked. i gave you my opinion.
if you want everyone to agree with you then you really shouldnt post in AIBU, as its probably not the best place.
you have backtracked considerably on the"'few months off every 6 months or so" thing, those were your words so i assumed you were being truthful.
i think, had you said your husband had one of these issues then i doubt you would have had a problem, but you have, im afraid, made your husband sound like an unreasonable man, on the one hand he is so religious he needs Sundays off, yet you admit he is not a practising catholic and he does not actually use those Sundays to go to mass, which if i were his colleague, working my share and his of the Sundays and i found this out i would be gobsmacked ) he is frequently off sick, which you have now backtracked on, and when he is at work he takes frequent breaks.
i think at some point your husbands employer would be within their rights to send him to see an independent medic for a full medical to see if he is fit for work. This has always been standard practice where i have worked if employees have a poor attendance record. Do they have an occupational health dept?
He perhaps isnt able to perform the role he was employed to do originally.That is not me being nasty, but i wouldnt want to work with your husband if i had to work more than my share of Sundays, cover for his frequent breaks and his frequent sickness, i would resent him not doing the same as other employees, this bullying, if it is indeed bullying, sounds like the management have got tired of it, and i agree they should deal with him entirely properly,but if i were his employee i would not be able to ignore it and let everyone else pick up the slack.