Normally concerned more with corporate balance sheets and earnings per share, The Street has an article today on the increase in discrimination suits being brought by Muslim employees, asking "What in Heaven's name is going on?" The piece offers some commonsense guidelines:
Employees must be given reasonable opportunity to engage in religious practices such as attending worship, prayer, wearing religious clothing or symbols, adhering to dietary rules, proselytizing, or refraining from activities that are contrary to their religious principles. Employers also must protect their workers from being harassed for their religion, and cannot retaliate against employees who complain of discrimination or participate in an investigation of another employee's complaint.
Things quickly get complicated, though, when employers attempt to apply the EEOC rules. Employers can usually prohibit employees from wearing religious clothing for safety reasons (scarves and machinery don't mix well), but usually cannot prohibit a sales clerk from wearing the same clothing to reduce the risk of customer discomfort.
Employees normally should be allowed to pray during their lunch and comfort breaks, but employers need not accommodate religiously based requests for special treatment that would put an unreasonable hardship on their businesses. (And no, grumbling from jealous co-workers doesn't usually rise to the level of unreasonable hardship.)
See EEOC guidelines regarding religious discrimination here.