In the mid-7th century, there were two types of Christianity in Britain: The British, the Scots and the Irish practiced 'Celtic Christianity'. Irish monks had also made this popular in Saxon Northumbria. Most of the Saxons practiced 'Roman Christianity' as used in Europe and by the Pope in Rome. Roman and Celtic Christianity were slightly different. They celebrated Easter at different times. This caused a big argument; especially in Northumbria where King Oswiu and his wife (from Kent) were on opposite sides. A bishop from Northumbria, named St. Wilfred, went to France and learnt all about Roman Christianity. On his return, he made a big fuss and said everyone must stop doing things the Celtic way. Eventually, in AD 664, King Oswiu decided to call a big meeting of churchmen, called a 'synod', at Whitby Abbey. St. Wilfred argued against St. Colman, the Bishop of Lindisfarne and he won. All the Saxons took up Roman Christianity.