But Christian leaders in Borno told the BBC that they felt their freedoms were under threat, and have embarked on three days of prayer and fasting in protest.
An enormous crowd has gathered in Maiduguri, the capital of Borno state in north-eastern Nigeria, to celebrate the adoption of Muslim Sharia law.
Several other states in the predominantly Muslim north of Nigeria have adopted Sharia this year, in apparent violation of an agreement with the federal government not to do so.
Christian leaders in Borno, who comprise a substantial minority, say they are strongly opposed to Sharia.
Reports from Maiduguri say there was a large police presence on the streets on Saturday.
Christians kept a low profile, closing their shops and businesses and choosing to stay at home.
Heavy rainfall disrupted the ceremony, but it did not prevent an enormous crowd of Muslims - estimated by one eyewitness as being in the hundreds of thousands - from gathering in the central square.
The governor of Borno state, Mala Kachalla, like other northern governors, has sought to reassure Christians by emphasising that Sharia, which includes punishments like amputation and flogging, will only apply to Muslims.
But Christian leaders in Borno told the BBC that they felt their freedoms were under threat, and have embarked on three days of prayer and fasting in protest.
The divisions which Sharia has opened up have provided Nigeria's new democratic government with one of its most difficult challenges.
In the city of Kaduna earlier this year more than 1,000 people were killed in fighting between Christians and Muslims.
Sharia has been supported by some northern politicians who are opposed to the government. But it also has massive popular appeal to those who believe it will help root out corruption and restore moral values.