The word "discrimination" carries in itself a negative connotation, implying that it would be unfair or unethical.
There are however, cases where "discrimination" would be justified and no one in their right mind would find the situation unfair. I'm not talking about lack of qualification (If I'm hiring a driver and I refuse someone for not having a drivers license, it's not discrimination), but about cases where the decision is made solely on ethnicity, race, religion, gender, sexual orientation, marital status or similar attributes, and could indeed be discriminative in a different context.
For example, in a movie about Napoleon the lead actor cannot be black, or a woman, etc. because he has to look similar to Napoleon. For a religious institution, or an organization of people of a certain political, ideological or social affiliation etc. it is also not unexpected to employ only people who belong to their group. I cannot become a rabbi if I'm not Jewish, and cannot become a Catholic priest without being Catholic. There are other similar cases where attributes which should not be considered a factor for an average job (like a factory worker) can be a factor and it's not unethical or unjust to discriminate in its case.