Last year, the Syrian-born psychiatrist, who has lived in the US for almost 20 years, catapulted herself into the centre of the critical issue of our time: how will Islam embrace modernity? She entered the battle of ideas in a fiery debate with an Islamic scholar on Al Jazeera television when she criticised Islam for its backwardness, for shunning knowledge and progress, for propagating a "mentality that belongs to the Middle Ages".
One question not often asked is why a growing number of Muslim women are speaking out, demanding a reformation of Islam. And the next question is why these brave women are not hailed as heroes and champions by Western leaders at the highest levels. They operate at the fringes on the right side of a crucial battle of ideas. It's still just a handful. Women such Ayaan Hirsi Ali, the Somalia-born former Dutch MP and author of Infidel, and Irshad Manji, African-born Canadian Muslim and author of The Trouble with Islam. And Sultan.
The answer to the latter question is one for us to ponder. Sultan is unapologetically curt as to why Muslim women are rising to the challenge: "Muslim women have lost everything. They have nothing to lose by speaking up." The security surrounding her visit to Australia last week attests to the fact women such as Sultan have, on the contrary, plenty to lose. They risk their lives when they speak out. Whether you agree with Sultan or not, her arguments about Islam ought to be met with words, not violence. Yet Sultan is used to constant security, FBI visits and daily death threats.
Late on Sunday evening she sent me a collection of them, including this: "I'm warning you to back up or the sword will cut off you're neck."
A crackpot, perhaps. But the slaughter of controversial filmmaker Theo van Gogh in The Netherlands, the heart of multicultural Europe no less, is a reminder that some crackpots deliver on their violent threats. Yet, for Sultan, the choice was obvious. She eschews Islam because, she says, it has so little to offer women. She describes Islam as a war against women, perverted by fear of sex and sexuality that mandates the mistreatment of women.
Sultan spoke to The Australian about her life. "I remember as a little girl trying hard to avoid passing by my father while he was praying because Mohammed once said that if a dog or a woman passes by a man while he was praying he had to rewash himself and pray again, otherwise his prayer wouldn't be accepted.
"I remember hearing as an eight-year-old girl that a woman is nothing but shame. Her marriage will cover up one-tenth of her shame and her grave will cover up the rest of it. Can you imagine, at eight, being consumed by shame just because you are female?" she asks.
Many find Sultan's message too confrontational. Her friends have asked her to soften her words. But she refuses, arguing that her experience as an Arab Muslim woman needs to be exposed. She says that before the Al Jazeera interview, her focus was on educating people in the Arabic world.
"In my (Arabic) writing, I always compare my life in Syria and my life in America, and I let my readers reach a conclusion ... they have never heard such voices as mine."
She receives hundreds of emails each week and thousands of people in Arabic countries click on to her website. She describes the world as a small village, thanks to the internet, where others have the chance to hear and understand what is going on
They see how women in the West are treated. "When they compare it with themselves, they question: 'Why? Why only us? Why don't we enjoy our lives they same way Western women do?"'
The Al Jazeera interview was the West's formal introduction to Sultan. And she attracts her fair share of Western critics. She is, some say, manipulated by Jews and Americans. But, as she points out, "the Islamic media introduced me to the West, not the other way around. Prior to my interview, I didn't have any Jewish friends. I said it because I believe it."
The American rabbi who walked out on Sultan at a conference complained that she failed to allude to a healthy, peaceful Islamic alternative.
Yet Sultan is certain that Islam can reform and will reform if exposed to enough information and if Muslims are able to make choices.
"Human beings look for the best, but many Muslims don't know the best ... they are hostages of their own belief system for many centuries and now I believe, because of the internet, they are exposed to different cultures, different thoughts, different belief systems ... if they are given the freedom to choose, I believe they are ready to mix Islam with other thoughts, to improve it," she says in a voice filled with passion.
But it will be a long battle of ideas.
"Look at any Islamic country. Tell me what you see. Poverty, backwardness, oppression, dictatorship, miserable lives. Somehow we have to help them change their way of thinking, their way of life. We have to re-create a new generation clean of hatred. We have been consumed by hatred. We are not practising our humanity. It's very sad."
Her message is clear. The West must be more confident about espousing its own values. And Islam must accept criticism as a sign of intellectual rigour if it is to reform into a belief system that embraces freedom and progress for its followers. Sultan is full of hope that the information revolution has cracked the wall around the Islamic prison. Not just for Muslim women.
I read another email she has translated from a 16-year-old Palestinian boy in Ramallah: "Without you, I would have been a suicide bomber. They taught me how to bomb, instead of teaching me to listen to music, or to enjoy looking at a beautiful painting. I don't believe you're human, you're a god."
Say what you will about Sultan's uncompromising message. She is part of a brigade of women, each in their own way dragging Islam into the 21stcentury.