All six of Germany's Muslim members of parliament voted in favour of same-sex marriage as Angela Merkel faced criticism for opposing the bill and announcing: "Marriage is between a man and a woman."
Despite the Chancellor's opposition, the historic “marriage for all” measure was approved with 393-226 votes in the Bundestag on Friday, leading hundreds of MPs to rise to their feet in a spontaneous standing ovation.
The Green Party, who launched rainbow confetti into the chamber when the result was announced, have since confirmed that the party has four Muslim lawmakers – Cem Özdemir, Ekin Deligöz, Özcan Mutlu and Omid Nouripour – who approved the legislation.
Aydan Özoğuz, a Muslim MP for the centre-left Social Democratic Party, also voted in favour of the bill after his party criticised Ms Merkel for "embarrassing" delays to the legislation.
The issue has divided the Chancellor's Christian Democratic Union (CDU/CSU) party, which remains the largest in the German parliament and has enjoyed comfortable poll leads and local election victories ahead of September’s federal elections.
Ms Merkel has always been unequivocal with her personal opposition to marriage equality, but her party's MP Cemile Giousouf, the first Muslim elected into the Bundestag in 2013, was praised on social media after endorsing the landmark measure.
Activist Filipe Henriques tweeted: “She's a Muslim woman and a Conservative. She voted for marriage equality, most of her CDU colleagues voted against.
“Merkel thinks marriage is sacred bond between men and woman. Most Germans and all Muslim MPs believe in equality. Who needs integration?”
Only three lawmakers are listed as being Muslim on the Bundestag website, but German newspaper Welt spoke to the parties and confirmed that all six consider themselves Muslim.
Ms Merkel said after the vote: “I hope that the vote today not only promotes respect between different opinions but also brings more social cohesion and peace.”
The Chancellor also said she supported the bill’s introduction of full adoption rights for same-sex couples – a move she had previously opposed – and was fighting anti-LGBT discrimination.
When opposing same-sex marriages she has cited German law, her values as an evangelical Christian and those of her party, which describes its foundations as the “Christian understanding between people and their accountability before God”.
In December 2015 the German leader claimed that multiculturalism was a "lie" and responded to criticism of her move to open the country's borders to one million refugees by saying: “We want and we will reduce the number of refugees noticeably.”
With almost all of its neighbours supporting legal unions between gay partners, calls had been increasing in Germany for the government to drop resistance that appeared increasingly anachronistic.
The Netherlands was the first European country to legalise same-sex marriage, back in 2001, followed by countries including Belgium, Spain, Canada, Norway, Sweden, Portugal, Iceland, Denmark, France and the UK.
Germany has allowed same-sex couples to enter civil partnerships since 2001, but same-sex marriages remained illegal.
The draft law legalising same-sex marriage was first moved in 2015 in the upper house of parliament by the state of Rhineland Palatinate.
It is expected to be signed into law by the President some time after 7 July but could face legal challenges.
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