* Justin Welby had swift rise through church hierarchy
* Faces tough decisions over gay marriage and women bishops
* Came to priesthood after career in oil business
By Alessandra Prentice
LONDON, Nov 9 (Reuters) - A former oil executive was named leader of the world's 80 million Anglicans on Friday, ending months of closed-door intrigue as the church struggles with bitter rifts over women bishops and gay marriage.
Justin Welby, 56, has been bishop of the northern English city of Durham for barely a year and will replace the liberal incumbent Rowan Williams as archbishop of Canterbury in December.
Welby is against gay marriage but favours the ordination of women as bishops.
Liberal clerics in the United States and Britain are at odds with conservatives in Africa and elsewhere over such issues, and Welby is likely to come under intense pressure to prevent the church tearing itself apart.
His appointment as the 105th archbishop caps a meteoric rise in the Church of England hierarchy since he quit the oil business and was ordained a priest in 1992.
The bespectacled and soft-spoken Welby accepted the appointment at London's Lambeth Palace, the official London residence of the archbishop of Canterbury for 800 years.
He said the job offer had been a daunting one. "My initial reaction was, 'oh no'," a smiling Welby told reporters in a room adorned with portraits of former archbishops and gold chandeliers.
"It's something I never expected. And the last few weeks have been a rather strange experience, to put it mildly."
The long-awaited announcement, made by Prime Minister David Cameron's office, follows weeks of intense speculation that a row over whether to choose a reformer or a safe pair of hands had stalled the nomination process.
"Well this is the best-kept secret since the last cabinet reshuffle," Welby told an audience that included his wife, five children and a baby grand-daughter, after opening his address with a brief prayer.
He has said the death of his infant daughter in a 1983 car crash brought him closer to God.
Speaking with the sleeves of his dog-collared clerical shirt rolled up to the elbows, Welby stressed that he wanted to be defined by his faith rather than his background - he attended Eton, the same elite British school as Cameron.
After a stint at French oil firm Elf Aquitaine, Welby worked as finance director at Enterprise Oil. But in his acceptance speech, he appeared wary of too much emphasis being placed on his former career.
"The key thing is the sense of having lived and worked in a world where the church was felt by many people to be completely irrelevant and how that attitude made you think round what it means to be Christian," he said.
Welby's handling of the issues of gay marriage and women's ordinations as bishops is set to define his tenure.
Commentators said his schooling, financial expertise and extensive conflict resolution work in Nigeria and elsewhere will have furnished him with the tough negotiation skills needed to heal the deep rifts in the church.
"I suspect he has that urbanity and confidence that you often associate with Old Etonians," said Richard Coles, an Anglican parish priest and broadcaster.
"He's worked at a high level that's not marked by sentimentality and gentleness, so I think he's also a player."
Cameron said Welby's corporate experience would stand him in good stead in the new role.
"Having someone who had a life outside the church in business, who understands difficult, complicated issues, will bring a great breath of fresh air to the Church of England," Cameron said, according to the BBC.
In his speech, Welby chose his words carefully when addressing the issue of gay marriage, highlighting the need for respectful dialogue. "We must have no truck with any form of homophobia, in any part of the church," he said.
He won praise from the liberal camp by saying he would vote to allow the ordination of women as bishops at a crucial assembly later this month that is the culmination of over 10 years of debate.
"I am thrilled," said Christina Rees, a former chairman of advocacy group Women and the Church and member of the General Synod, the legislative body of the church.
"To hear the new archbishop of Canterbury saying 10 days before the vote: 'I am strongly in favour', is really going to positively influence the vote," Rees said.
After his speech, the archbishop-to-be smiled widely as he posed for photographs at the imposing entrance to Lambeth Palace, across the river from the Houses of Parliament and Big Ben. He will be formally enthroned as archbishop next year.
"All archbishops of Canterbury get eaten alive by their own kind," said Coles.
"Whether or not Welby survives, remains to be seen."