Discussing religious law is a sensitive topic in many Muslim countries. But on Twitter, a hashtag which translates as "why we reject Sharia" has been used 5,000 times in 24 hours. The conversation is mainly taking place in Saudi Arabia and Egypt. The debate is about whether religious law is suitable for the needs of Arab countries and modern legal systems.Dr Alyaa Gad, an Egyptian doctor living in Switzerland, started the hashtag. "I have nothing against religion," she tells BBC Trending, but says she is against "using it as a political system". Political Islamists often call for legal systems to be reformed to be consistent with Sharia principles, and some want harsh interpretations of criminal punishments to be implemented. Dr Gad says she is worried about young people adopting the extremes of this kind of thinking. "You see it everywhere now, the Islamic State is spreading mentally as well as physically" she told BBC Trending.One of Dr Gad's tweets compared what action is taken against those who commit crimes under strict interpretations of Sharia law to those who do so in Western societies.The Tweet says: "A thief under Sharia rule has his hand cut off and becomes a burden on society - and a Norwegian criminal is rehabilitated to become a good citizen"Many others joined in the conversation, using the hashtag, listing reasons why Arabs and Muslims should abandon Sharia. "Because there's not a single positive example of it bringing justice and equality," one man tweeted. "Because IS and Somalia and Afghanistan implement it, and we've seen the results," commented another. A few Saudis who joined the online conversation shared their experience of coming from a country that adheres to Islamic law. "In Saudi Arabia we tried implementing Sharia, and know first-hand the bitterness of being ruled by a religious power," a Saudi man living in California tweeted. And a Saudi woman commented: "By adhering to Sharia we are adhering to inhumane laws. Saudi Arabia is saturated with the blood of those executed by Sharia".The caption for this cartoon reads: "Marrying four [women] and underage girls and slaves is moral. But a consensual relationship between two unmarried people is immoral and against Islam".However a large proportion of those tweeting were less critical. They argued that the problem was not religious law per se, but a flawed understanding and interpretation of it. An Egyptian living in Bahrain tweeted: "There has never been anything wrong with Sharia, but it's how we implement it". Another Egyptian commented: "There is no singular understanding of Sharia. The Muslim Brotherhood have one understanding, the Salafis have another and so do IS, Boko Haram and Al-Qaeda".Others found the hashtag to be offensive to Muslims. Dr Gad, who started it, was called a "non-believer". Another commented: "You don't want Sharia because you want homosexuality, alcohol and adultery".Dr Gad, who has a popular YouTube channel that discusses sexuality and health issues, says she is used to this kind of reaction to the topics she initiates. She says one of the reasons she started the hashtag is because she values her right to speak out - a right she says her friends back in Egypt don't have in the same way. "If I were living in Egypt I would not be half as courageous as I am now," she says.Bakudaily.Az