Since the September 11 attacks on the United States, being a Muslim in America is undeniably harder. From 2010 to 2013, seven states passed legislation to outlaw Sharia, despite the fact the Islamic code applies to Muslims only, and Muslims, like all Americans, are ultimately subject to state and federal law.

In his book, What is an American Muslim? Embracing Faith and Citizenship, published this year by Oxford University Press, Charles Howard Candler Professor of Law Abdullahi Ahmed An-Na’im argues that Islam is protected by the establishment clause like all other religions, but also that when a state attempts to enforce Sharia as law, it robs Muslims of freely practicing their faith.

“As a Muslim I need the state to be secular,” he says. “Because when it is secular I can be more honest — when I do something I will do it because I believe it is my duty to do so and I choose to, not because I am afraid of the state.”

The US courts’ long history of interpreting religious issues makes it possible to be both a devout Muslim and a fully engaged American citizen, An-Na’im says.

“In this country there is a wealth of tradition of how to negotiate these questions,” he says. “Other traditions have had to negotiate similar issues and that became the pool of experience that Muslims can draw upon.”

Islam is the second largest religion in the world, with 1.6 billion adherents who represent the majority population in 49 countries. In 2011, there were 2.75 million Muslims living in the US, according to Pew Research Center. In his book, An-Na’im works to counter the idea that American Muslims are a monolithic bloc whose religious practice dominates their public and civic lives. In America, the Muslim population is very diverse — including black, white, and Asian citizens who came to the US from many different countries and cultures. Just as with Catholic or Mormon Americans, their faith is one dimension, albeit an important one, of their citizenship.

Shortly after Oklahoma’s 2010 law banning Sharia was struck down by the Tenth US Circuit Court of Appeals, An-Na’im spoke at Saint Louis University School of Law on the issue.

“The term Sharia does not occur in the Quran at all in the meaning that we use it today,” he told the audience. “In fact, the term Sharia does not exist in Muslim sources for the first 300 years of Islam,” he said. And when governments attempt to enforce it as law, it is no longer religion.

“The principle ceases to be Sharia by its enactment into statutory law. It becomes something else,” he says.

While a student at the University of Khartoum, An-Na’im met Mahmoud Mohammed Taha, a man he has referred to as his moral father. “He enabled me to understand the Quran differently,” An-Na’im says.

“When we understand the whole Quran in the context of the twentieth century, we see that the question of the equality of women is obvious, and you cannot morally defend inequality or morally defend violation of freedom of religion,” An-Na’im says.

An-Na’im was raised in a Muslim country and once believed that Sharia could be administered by the state. But he also saw how extremism could warp religion. In 1985, Taha was convicted of heresy and sedition for distributing a pamphlet protesting the imposition of Sharia in Sudan by then president Jaafar al-Nimeiri. Ten days later, after refusing to recant, the 76-year-old was hanged.

“What I have come to understand and think more recently over the past 10 to 15 years is that whatever the content of Sharia, it is for Muslims to live in their societies but not for the state to enforce,” he says. “No matter how humane or civilized we think the content of that religious code is, religion is for people to observe in their private lives outside the state.”An-Na’im led Human Rights Watch/Africa from 1993 to 1995.

“I see no contradiction whatsoever between being a Muslim and being a human rights advocate,” he says. He sees Sharia’s evolution as not unlike the gradual adoption of the 1948 Universal Declaration of Human Rights. “[It is] a minimum standard of decency and simple human dignity that all human societies must abide by. But when you get to what are the rights and what do they mean, generally you get disagreement,” he says.

One such disagreement is what constitutes cruel and inhuman punishment. While all members of the European Union do not allow the death penalty, it took decades for some countries to arrive there, An-Na’im says. In the United States, the death penalty is considered a valid punishment for certain crimes, even though some states have abolished it.

“It shows America and Europe can disagree about what is a human right,” An-Na’im says. “By the same token, other parts of the world may have other disagreements about what human rights are in other fields.”

“I am not a relativist in the sense that I say we should let every society decide for itself,” he says.

“But rather my point is about consensus building. I call for accepting disagreements like those as something that is normal among human society, and engaging in the negotiating process so you can come to agreement.”

An-Na’im says he and other Muslims seek to interpret Sharia from within the Islamic tradition, “not so that the state can enforce it, but to reform it so that Muslims can live it in a way that is also consistent with human rights.”