Answer:
There is no single way to measure how culturally diverse a country is.
India has more languages in daily use and more different religions and cultures than any other country.
Canada and the United States are both culturally diverse countries with large populations who are immigrants and many people who do not speak the primary languages or adhere to the cultural norms of the majority.
Indonesia has tremendous cultural diversity scattered among hundreds of islands.
Some countries are culturally diverse in that they have multiple roughly equal cultures within their borders. Macedonia and Montenegro are examples.