You shouldn’t assume things. For example, when you are not sure about someone’s religion, you shouldn’t even try celebrating the religious days of their religion. Assuming is one of the worst strategies in cross-cultural communication. It creates awkward moments. Unless you explicitly ask, hypothetical approaches will always be based on stereotypes. But people are not stereotypical.
Having a diverse workforce is a crucial step for many companies. Leaders in these companies need to build trust with many different cultures. That’s why leaders have to learn when to ask explicitly and how to read between lines. As a practice, ask yourself “is this knowledge come from my assumptions, or did I ask explicitly about it, or did I hear them talking about it before?”