I was always taught to avoid three topics in polite company: religion, money, and politics. Fortunately, the workplace is not polite company, quite the contrary, so I suppose all three topics are theoretically fair game! However, a recent lawsuit filed in California begs to differ, and from where I sit, they've hit the nail right on the head.
Employees at Diskeeper were required by their CEO to attend Scientology-based training sessions as part of their employment. One employee took particular exception to this rule and expressed his disagreement. The CEO, a rather devout Scientologist, insisted that this was "non-negotiable" and that the employee must attend as a condition of employment.
The employer took the issue to his manager, who supported the employee. As a result, both employees were subsequently dismissed. As one might guess, they are both suing Diskeeper for religious discrimination and employment law violations.
Assuming that the details in the suit are true and accurate, this should be a shut-and-closed case. Employers, no matter how large their salary, ego, or religious conviction, simply cannot force their employees to submit to propaganda promoting the CEO's religion.
If you really need an explanation as to why, then I'm not really sure my explanation would suffice. Quite simply, it is unethical to expect one's employees to have the same religious beliefs and practices as yours. In fact, those beliefs and practices have nothing to do with one's employment and should be kept to one's self.
Though the CEO of Diskeeper may feel that I'm intolerant by holding such views; my views would keep people employed for their talents rather than sacked for their beliefs.