So should a Jewish receptionist have to take off his kippah?
Yes an employer should be allowed to decline to employ somebody who insists on wearing any religious dress or jewelry.
many religious people feel their religious beliefs carry over to all aspects of their lives, including their places of employment.
Belief is not an issue.
What if the employer bans religious symbols such as the hijab, but allows someone to wear a jewelry with a cross?
That would be discrimination.
What if the employer is adept of a certain religion and wishes to have its religious symbol at the workplace. Can an employee of a different religion feel offended ...
Yes
...and demand that the symbol is withdrawn?
No