Think of the ramifications of such a law.
I own a private business and catch my employee telling customers not shop at my store but to shop at my competitors store. I fire him and thanks to your amendment to the Civil Rights laws, I get charged for violating his free speech rights.
I own a private business that prepares pork products. I have an employee that just converted to Islam or Judaism and refuses to touch the pork food stuffs. I fire them because they are no longer able to or simply refuse to do the job for which they were hired. I get charged for infringing on their exercise of religion.
I refuse to allow an employee to carry a weapon on my private property. I get charged.
I dock a workers pay without a jury trial. I get charged.
The possibility of abuse is limitless.