Portuguese functions as a state language. Virtually all formal documents and official declarations are stated in Portuguese. But it is not the first language. Cape Verdean, commonly called Creolo, is spoken as a mother tongue by virtually all Cape Verdeans, irrespective of social status or religious affiliation. Moreover, historical linguists often attribute Cape Verdean Creole as the oldest "New World" contact language. It is a "contact" language in the sense that it was birthed and evolved between linguistically different groups who, by necessity, had to create a common language to communicate with each other. There is a rich repertoire of literature and songs in Cape Verdean Creole. In religion, the majority of Cape Verdeans follow Catholic Christianity. There are some Protestants, Baháʼís and Muslims.