Why some Dutch or european are converting to Islam?

1- Despite being negatively presented in the media and elsewhere, Islam has won thousands of new followers in many European countries. Although many would stereotypically associate jihadist terrorists as Arabs or South Asians, European converts have actually participated in most terrorist plots and actual attacks that have taken place on European soil since 9/11.

While at least 40 European converts have turned into jihadist terrorists, a much larger number of them have been mobilized around Islamic issues. Being familiar with the political culture and system of government of their own countries, many converts have been involved in Islamic activism, defending Muslim rights and in some cases propagating Islamist messages. Having diverse agendas, organizations which are run by converts cannot be treated as a monolithic world. The IPB and the FIS have been outright Islamist groups, whereas AOBM, IBS, and AMG have mostly focused on social, religious and cultural issues.

source: https://ctc.usma.edu/islamic-activism-in-europe-the-role-of-converts/

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2- Joram van Klaveren was an MP from 2010 until 2017 for the far-right Party for Freedom (PVV) led by anti-Islam and anti-immigration firebrand Geert Wilders. Mr van Klaveren once fiercely advocated Mr Wilders' policies of banning the Koran and closing down mosques.
However, he has now said that he discovered out he had more in common with Islam than he initially thought when he started research for a book criticising the religion, which caused him to completely change his view.
Mr van Klaveren said: "I looked at the Bible on my bookshelf, on the table were books about the Prophet Muhammad.
"The prior years I had a big aversion to Islam. When you then have to conclude that you were wrong, it is not a fun moment. But while searching for God I always felt a certain unease. And that slowly disappeared. It felt a bit like coming home in a religious way."
For seven years Joram van Klaveren fought a relentless campaign in the Lower House against Islam in the Netherlands
Geert Wilders, right, has become notorious for his anti-Islam policies  CREDIT: MARTIJN BEEKMAN / ANP / AFP
Mr van Klaveren, who grew up in a reformed protestant family, said he is "very sorry that he contributed to giving people a false image about Islam".
He said that the manuscript of the Islam-critical book he initially planned to write has since been thrown into the bin and will be replaced by a book in which he will counter the arguments of critics of Islam.
Mr van Klaveren said that the analysis which he made as a far-Right MP that most problems in the country and the world can be blamed on Islam were false.
He said: "That was just the policy of the Party for Freedom: everything which was not right had to be linked one way or another to Islam."
Mr van Klaveren said he "did not suddenly become a Lefty" and that his conversion is purely a personal religious matter.
source: https://www.telegraph.co.uk/news/2019/02/05/dutch-former-anti-islam-mp-says-become-muslim/

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3-In France, estimates suggest approximately 50,000 to 100,000 converts out of a population of three to four million Muslims. For details, see Mapping the Global Muslim Population (Washington, D.C.: Pew Research Center, 2009). In 2006, there were 850,000 Muslims in the Netherlands, including 12,000 converts. For details, see “More than 850 Thousand Muslims in the Netherlands,” Centraal Bureau voor de Statistiek, October 27, 2007. In Germany, the estimated number of converts ranges from 12,000 to 100,000, with the total Muslim population set at around three million. For details, see Johannes Kandel, “Organisierter Islam in Deutschland und gesellschaftliche Integration,” Friedrich Ebert Stiftung, September 2004. In Great Britain, there were about 63,000 native converts out of a population of 1.6 million Muslims in the early 2000s. For details, see the 2001 Census completed by the Office for National Statistics. Their numbers, however, must have increased because the Muslim population as a whole reached 2.4 million in 2009. For details, see Richard Kerbaj, “Muslim Population Rising 10 Times Faster Than Rest of Society,” The Times, January 30, 2009. Spain has an estimated 800,000 Muslims, roughly 20,000 of whom are converts. For details, see Geoff Pingree and Lisa Abend, “In Spain, Dismay at Muslim Converts Holding Sway,” Christian Science Monitor, November 7, 2006
source:https://ctc.usma.edu/islamic-activism-in-europe-the-role-of-converts/