Final answer:
The primary law protecting against religious discrimination in the workplace is Title VII of the Civil Rights Act of 1964, which prohibits employment discrimination based on religion and other protected characteristics.
Step-by-step explanation:
The primary law prohibiting religious discrimination in the private sector workplace is Title VII of the Civil Rights Act of 1964. Under Title VII, it is unlawful to discriminate against individuals in employment matters on the basis of their religion, as well as race, color, sex, or national origin. This includes practices such as hiring, firing, promotions, salary, job training, and other terms of employment. Additionally, Title VII prohibits workplace or job segregation based on religion, ensuring that employees are not assigned to certain positions based on religious garb, grooming practices, or perceived customer preferences.