Am I justified in refusing to come in for work on a specific holiday because of my religion?

Certain holidays such as Easter, and Christmas I refuse to work on. Those aren’t just commercial holidays to me. I was told I had to work on Easter and it effected me emotionally because it’s an important day in Christian religion, and it’s a day of worship. I do not think we should be fired for our religion beliefs and the importance of certain days in our religion history. Jobs should have a sign up sheet for those who wish to get paid holiday instead of forcing employees to work. What do you think?

Of course I understand jobs such as nurses, etc working on holidays but in retail, I think it is unnecessary. Most of the time, they are paying employees more than making a profit on those days. If I am willing to work on other holidays besides 2 out of the year, it should not be problem.