Every institution and organization has a culture. Your family has a culture. Your workplace has a culture. Your house of worship has a culture. Your favorite restaurant has a culture. There are many academic definitions of the word culture. For our purposes, let's define it as those beliefs, values, habits, patterns, practices, symbols, rituals, and norms that define an organization or institution. If every Thanksgiving your family eats turkey and ham, and everyone plays a game of backyard tag football, those two activities are part of your family's culture. If you are the one that carves the turkey with a special knife, then that practice of carving the turkey, and the special carving knife, are part of your family's Thanksgiving culture.
An institution and organization will have more than one culture. At a school, for example, there may be an "athletic culture" that embodies the values, habits, and practices that characterize the athletic teams. There may also be an "academic culture" and a "relational culture" that create a shared sense of identity and association with the institution. The interesting thing, is that these cultures are always racialized. What I mean, is that because cultures are developed and enacted by people, people bring their racial and ethnic selves to whatever culture is being built or expressed and the culture bears the imprint of those artifacts and practices that are associated with a particular race.
In other words, if the definers of culture in your organization--its leaders, influencers, and core constituents, are mostly white, then your organizational culture will reflect the norms, practices, and aesthetics characteristic of white culture(s). And yes, just like Asians, Hispanics, and black people have cultures, white Americans also have cultures. For example, at two predominantly white Christian schools where I was employed, the music being played in the front office was CCM worship, the acoustic and more guitar driven music produced and performed by predominantly white musical artists. Most black Christians, however, traditionally listen to gospel music. Piano, organ, and drums define this genre, and it sounds more like Earth, Wind, and Fire, than Johnny Cash.
One is not better than the other, but when prospective diverse candidates applying for jobs visit the campus, or potential minority families come to visit, they notice these aspects of your culture. Churches that claim to want diversity but refuse to vary their music or place people on stage who can represent aspects of a different culture are sending a strong message to people of other racial and ethnic backgrounds. The message is this: "You are welcome here if you become, and only if you become, just like us."
This kind of assimilation is not the kind of multiculturalism that leads to the "beloved community" that Dr. Martin Luther King, Jr. envisioned. True belonging and inclusion means that I can do more than sit at the table. It means that there's something served that I like to eat. If your organization is not serving the type of cultural diversity that invites others in people from those cultures will hesitate before entering, wondering what the cost of the clash will be.
This means that your organization needs to undergo a "culture audit." What cultural messages are you sending that may alienate others or suggest a certain type of racial/ethnic exclusivity? When you discover these cultural messages, modify them by adding elements from other racial/ethnic cultures. You don't have to discard your main culture, because there will always be a "main stream" flowing through an organization. But if you don't allow for other aqueducts and tributaries to flow into that stream, depositing their own contributions, practices, aesthetics, and norms, then true diversity and inclusion will remain elusive.