It depends. If you are an employer, there is no way you can control the spread of religion and you don't have any business what your employees do after working hours. Islam is spreading in the Western Christian world, not so much due to proselytization but it has so much to do with forced immigration.
Therefore, apart from Christianity, you must be ready for other religions invading the workplace pretty soon. So, how do you deal with it?
First of all, remember that this country guarantees freedom of religion. The First Amendment to the United States Constitution specifies that everyone in the U.S. has the right to practice his or her own religion, or no religion at all.
So, there are many people in this wide and broad country that practice Christmas, Kwanzaa, Hanukkah and Ramadan since in the past, the United States has been regarded as the melting pot of the world.
However, that guarantee can also be a two-edged sword. You cannot force someone to adhere to your religion, but the other person is also prohibited from forcing his into yours.
The workplace is therefore affected, whether employers like it or not. There is now the question: should a Christmas tree be used as a decoration on the office table, or a menorah, or both or nothing at all?
A recent Gallup poll indicates that 80 percent of Americans still identify with a particular religious faith. Thus, the workplace inevitably becomes the ground where conflicts in religion arise. The workplace has experienced about 43 percent of such conflicts starting in 1990.
So, as an employer, it depends on the situation whether to allow or not allow religion into your workplace. Certainly, you should not base your hiring on one's religion alone. But when it comes to publicly displaying religious practices on your particular workplace or office and proselytization, that is where you need to draw the line.