While campaigning last year to become Rio de Janeiro’s mayor, Marcelo Crivella, a retired Pentecostal bishop, insisted his faith would not get in the way of governing the nation’s most famous city. The former gospel singer and missionary, a high-profile member of one of Brazil’s most powerful evangelical churches, captured 59 percent of the vote and took office Jan. 1. But less than two months into his four-year term, Crivella’s promises are about to be tested by Carnival, Rio’s annual weeklong party often marked by heavy drinking and drug use, wild sex and round-the-clock dancing.