No I would be for any private orginization to hire anyone they want. And if the person agrees to follow certain guidlines even if moral, that would be OK as well. Has to do with the whole freedom thing.
Would a Christian relief organization want satanist working for them? What if someone converted later. What if one of the relief workers was having intercourse with some of the people they were trying to help? These kind of things can reflect badly on any religious organization and even some that are not. As long as it is applied equally among all employees and does not result in breaking Federal guidelines for discrimination. No one should have a problem.