Can your boss keep you from taking a half day tomorrow in observance of good friday?

Only if you want to keep the job.
no, you can always quit
Unless you have a contract, employment is a new contract every day. It can change every day and you are free to accept it (if offered) or reject it. The few limitations are found in the fair labor standards act, minimum wage laws, etc. No law requires a private employer to give a damn about your religion or your home life in any way. Similarly, if you were to hire someone to work for you, such a to clean your home, you can offer that employment with just about any condition you wish.
Since Good Friday is Christian holiday you bet.
If however you were observing a Muslim holiday you get the time off with double the pay as not to offend you.
Yes, it is not personal, it is business. I am not saying it is right, but it is legal.
Did you request half a day's vacation?


Answer:
yes if it interfers with business!!!
Yes, unless you work for a fast food chain like McDonalds; if the latter is true, be sure to request fries with the half-day off.
It's completely up to your boss.
No, that is more than likely a violation of some sort of company policy. If you have to work, then you should let your boss and your bosses boss know that you don't feel right having to work on Good Friday, your best bet is to write a memo.

If all else fails call in sick.