I strongly suggest that when filing a union grievance, and when appealing your unemployment benefits, and in all ways trying to pursue this further, you leave out the issue of the "beard for religious reasons" as much as you can. It sounds as though your employer was trying to get rid of you. That you had a beard was one of the things they tried to use. Without asking, they figured you definitely belonged to the first church of "You can't tell me what to do!" and you'd fight them on this beard issue and be fired for it. Then they decided to try another tack, which is going to be something fought through with the union, it sounds like. Age discrimination is not going to be an issue. Being a high earner or a long term employee isn't a protected category.
But it's sounding less and less like discrimination on religious grounds is going to be a viable argument for you. They want rid of you. You must realize that if you are reinstated, they'll keep trying, will be watching you very closely for something they can legitimately use to terminate you. Because for some reason, they want to, and that's pretty much legal. You have the right to quit, the right to look for other jobs even while still working with them. That's the best way to leave a situation such as you describe here.
If it does come down to your being reinstated with pay by your union's intervention, you will have to pay back any unemployment benefits you have received in the interim, but certainly keep that going while you are working with the union on this issue. You need the quick income provided by unemployment benefits IF they are approved.