Pope Benedict XVI has arrived in Benin, on his second visit to Africa which has the world's fastest-growing Roman Catholic population.Huge crowds welcomed the pontiff at the airport in the city of Cotonou.Although the number of Catholics in Benin is rising quickly, the majority of the population follow Voodoo, which was taken by slaves to the Caribbean.Upon arrival, the Pope urged Africans to avoid the "unconditional surrender to the law of the market and finance"."Modernity must not cause fear, but it cannot be built by forgetting the past," he said.The pontiff also spoke of avoiding "exacerbated and useless nationalism or tribalism that can become deadly, extreme politicisation, inter-religious tensions to the detriment of the common good or finally the erosion of human, cultural, ethical and religious values".During his visit, the Pope is also likely to face questions about condoms.On his 2009 visit to Africa, he sparked outrage among Aids activists by saying that handing out condoms could speed up the spread of HIV in the continent worst hit by the virus.Snake-god templePope Benedict was greeted by a 21-gun salute after he landed in Cotonou, Benin's largest city.Among those waiting for the pontiff at the airport were several hundred women, wearing dresses adorned with images of the Pope's face. Many others had blue, green, red and yellow headscarves, representing different parishes."It's a joy for us, we are happy and there will be a big celebration, which should bring a lot of faith to all faithful people in Benin," city resident Noelle Agboton was quoted as saying by Reuters news agency.Friday has been declared a public holiday, Cotonou's streets have been cleaned and buildings are adorned with posters welcoming the Pope.The BBC's Tomi Oladipo in Cotonou says there is huge excitement across the country.Pope Benedict is to visit the city of Ouidah on Saturday, where there is a Voodoo museum.Benin is widely seen as the home of Voodoo, and the religion is followed by some 40% of the country's population.Some 27% classify themselves as Christians and 22% Muslims, but correspondents say many of these people combine Voodoo practices with either Christianity or Islam.However, local people say their religion has nothing to do with sorcery or black magic, or the depiction of Voodoo in Western films.Catholic missionaries first arrived in Ouidah 150 years ago and the city boasts the largest Catholic seminary in West Africa.The city's cathedral was built on land which was originally a Voodoo "sacred bush" - where offerings are made to the gods. It now overlooks a temple where the snake-god is worshipped.High-ranking Voodoo priests have been invited to meet the Pope.Some 10,000 pilgrims are expected to travel from neighbouring countries in the hope of seeing the pontiff.The Pope is expected to address the questions of human rights, justice and reconciliation on the conflict-ridden continent.On Saturday, he is to sign a formal apostolic exhortation entitled The Pledge for Africa (Africae Munus in Latin), which covers these subjects."May this document fall into the ground and take root, grow and bear much fruit," the Pope said upon his arrival.