Question: Why is it believed that Denmark became Christian?
About the article "Denmark", section "Viking and Middle Ages".

Candidate passages:
Lund () is a city in the province of Scania, southern Sweden.
The town has 82,800 inhabitants in 2010, out of a municipal total of 110,824.
It is the seat of Lund Municipality, Skåne County.
The city is believed to have been founded around 990, when Scania belonged to Denmark.
It soon became a major Christian center of the Baltic Sea region, at a time when the area was still a frontier area for Christian mission, and within Scandinavia and especially Denmark through the Middle Ages.
From 1103 it was the seat of an archbishop.
At the center of the city stands the towering Lund Cathedral, built ca 1090–1145.
Lund University, established 1666, is today one of Scandinavia's largest institutions for education and research. 
From the 8th to the 10th century, the Danes, as well as Norwegians and Swedes, were known as Vikings.
They colonised, raided, and traded in all parts of Europe.
Viking explorers first discovered Iceland by accident in the 9th century, on the way towards the Faroe Islands and eventually came across "Vinland" (Land of wine), also known today as Newfoundland, a province in Canada.
The Danish Vikings were most active in the British Isles and Western Europe.
They conquered and settled parts of England (known as the Danelaw) under King Sweyn Forkbeard in 1013, Ireland, and France where they founded Normandy.
More Anglo-Saxon pence of this period have been found in Denmark than in England.
As attested by the Jelling stones, the Danes were united and Christianised about 965 by Harald Bluetooth.
It is believed that Denmark became Christian for political reasons so as not to get invaded by the rising Christian power in Europe, Germania, which was an important trading area for the Danes.
In that case Harald built six fortresses around Denmark called Trelleborg and built a further Danevirke.
In the early 11th century, Canute the Great won and united Denmark, England, and Norway for almost 30 years.
Throughout the High and Late Middle Ages, Denmark also included Skåneland (Skåne, Halland, and Blekinge) and Danish kings ruled Danish Estonia, as well as the duchies of Schleswig and Holstein.
Most of the latter two now form the state of Schleswig-Holstein in northern Germany.
In 1397, Denmark entered into a personal union with Norway and Sweden, united under Queen Margaret I.
The three countries were to be treated as equals in the union.
However, even from the start Margaret may not have been so idealistic—treating Denmark as the clear "senior" partner of the union.
Thus, much of the next 125 years of Scandinavian history revolves around this union, with Sweden breaking off and being re-conquered repeatedly.
The issue was for practical purposes resolved on 17 June 1523, as Swedish King Gustav Vasa conquered the city of Stockholm.
The Protestant Reformation came to Scandinavia in the 1530s, and following the Count's Feud civil war, Denmark converted to Lutheranism in 1536.
Later that year, Denmark entered into a union with Norway.
This is a list of Danish monarchs, that is, the Kings and Queens regnant of Denmark.
This includes:  The Kingdom of Denmark (up to 1397) * Personal union of Denmark and Norway (1380–1397)  The Kalmar Union (1397–1536) *Union of Denmark, Norway and Sweden (1397–1523) *Union of Denmark and Norway (1523–1536)  The Kingdom of Denmark-Norway (1536–1814)  The Kingdom of Denmark (1814 to present) * Iceland (since the union between Denmark and Norway in 1380.
Independent in a personal union with Denmark 1918–1944.
A sovereign republic since 1944.)
* Greenland (since the union between Denmark and Norway in 1380.
Effective Danish control began in 1721.
Integrated into the Danish realm in 1953.
Internal home rule introduced 1979.
Self-determination assumed in 2009.)
* Faroe Islands (since the union between Denmark and Norway in 1380.
County of Denmark 1816–1948.
Internal home rule introduced 1948.)
The house of Oldenburg held the Danish Crown between 1448 and 1863, when it passed to the house of Schleswig-Holstein-Sonderburg-Glücksburg, a cadet branch of the same house, descended from King Christian III of Denmark.
The kingdom had been elective (although the eldest son or brother of the previous king was usually elected) until 1660, when it became hereditary and absolutist.
Until 1864 Denmark was also united in a personal union with the duchies of Schleswig and Holstein. 
Ancient people believed that the flesh of a peafowl did not decay after death, and it so became a symbol of immortality.
This symbolism was adopted by early Christianity, and thus many early Christian paintings and mosaics show the peacock.
The peacock is still used in the Easter season especially in the east. 
Sigbrit Willoms was born into a merchant family from Amsterdam, but moved to Bergen, Norway, in 1507.
She was the mother of Dyveke Sigbritsdatter, who met the future Danish King Christian II in Bergen.
Mother and daughter moved with the king to Copenhagen in 1513.
Her influence over the king became greater after the death of her daughter in 1517, and from 1519 to 1523, she was accounted the most politically influential person in Denmark.
Sigbrit was in charge of the court of Prince Hans and of customs and the treasury, and the house keeper of the court of the queen.
She was given the title "Mother Sigbrit" and had the de facto position of minister of finance.
Being a bourgeoise, she was known for forwarding the interests of the middle classes.
She was unpopular with the nobility, and was seen by some as the person behind the Stockholm Bloodbath in 1520.
Her enemies spread rumors that she was a witch because of her herbal knowledge.
In 1522, she instigated a new law about hygiene in the city, where people were told to have their houses cleaned every week.
When King Christian was driven out of Denmark in 1523, Sigbrit followed him to the Netherlands, where Christian asked for aid from his brother-in-law, the emperor.
The emperor made the condition that Christian was to get rid of Sigbrit, which Christian agreed to.
The date and circumstances of her death are unconfirmed.
In 1532, a woman was detained in a prison in the Netherlands, who is believed to have been Sigbrit.
The emperor wished to have this prisoner executed for witchcraft.
It is not known if she was.