(CNN) -- Nigerian President Goodluck Jonathan, a Christian from the south, was sworn-in on Sunday as his country tries to bounce back from violence unleashed last month by an Islamist sect.
Boko Haram, an Islamic group that has challenged Nigerian government, is believed to be behind a series of bombings in the wake of Jonathan's re-election.
This will be Jonathan's first full term; as vice president, he took over the presidency in May 2010 upon the death of then-President Umaru Yar'Adua, who had suffered from a heart condition.
In keeping with his name, he is regarded as one of the luckiest men in Nigerian politics. Jonathan, 53, with a degree in zoology, worked as an environmental officer until he entered politics. He ran as deputy governor for Bayelsa state in 2001-- one of Nigeria's main oil-producing states in the oil-rich Niger Delta region.
After the state governor -- Diepreye Alamieyeseigha -- was indicted by Nigeria's Economic and Financial Crimes Commission on corruption charges in 2006, Jonathan was promoted to governor of one of the richest regions in Africa.
He is widely regarded as having been hand-picked by then-President Olusegun Obasanjo to run as vice-president with Yar'Adua in the 2007 national elections. They won what was considered perhaps the most flawed election in Nigerian history.
This year's win by Jonathan, who is from the majority-Christian southern part of the country, sparked violence in the Muslim-dominated north.
Explosions in Nigeria's northeastern state of Borno killed a few and wounded dozens in late April in the days leading up to national governorship elections in attacks that police described as attempts to intimidate voters who had picked Jonathan.
Northern Muslims in some areas charged that the presidential election was rigged. Armed protesters in the region took to the streets chanting the name of former military ruler Muhammadu Buhari, the main opposition front-runner.
The last election, four years ago, was widely condemned for rampant vote rigging, violence, theft of ballot boxes and intimidation.
While this year's presidential election was marred by violence, reports of underage voting and logistical problems, observers said they considered it an improvement.
After he was declared the victor, Jonathan warned that persistent post-election violence could threaten the stability of the country.
"These acts of mayhem are sad reminders of the events which plunged our country into 30 months of an unfortunate civil war," Jonathan said last week.
Jonathan was referring to a period of unrest in the 1960s that spawned a civil war in Nigeria.
Nigeria is Africa's largest oil producer and its most populous nation, with 150 million people.
CNN's Christian Purefoy contributed to this report.