The standard account of Uruguayan religion, that a state secularised itself thoroughly and a population followed, is accurate about the churches and misses what grew in the space.
Afro Brazilian religions crossed the border from Rio Grande do Sul from around the middle of the twentieth century, and their Uruguayan following is now substantial. Two strands are distinguished locally. Umbanda combines Kardecist spiritism, Catholic imagery and Afro Brazilian orisha material, and works through possession by spirit types such as the preto velho, the old African, and the caboclo, an indigenous figure. Batuque, also called Africanismo, is the older and more strictly initiatory form, closer to the Yoruba derived practice of Bahia and Porto Alegre, with a priesthood, animal offering and a longer training.
The temples, the terreiros, are counted in the hundreds. Their following is drawn substantially from working class Montevideo and from people whose formal affiliation, if asked in a census, would be none.
The most visible expression is the night of 2 February, when tens of thousands gather on Playa Ramirez and other Montevideo beaches with candles, flowers, small boats and offerings for Yemanja, the orisha of the sea, and carry them into the water at midnight. It is now large enough to be managed by the municipality as a public event.
Two things follow that are worth stating. Secularisation in Uruguay reduced the authority of the churches without producing a population uninterested in religious practice. And the fastest growing tradition in the most secular country in the Americas is an African derived one, which is not what most theories of secularisation would have predicted.