In March, hundreds of extremists rallied in Jakarta in support of the Islamic State of Iraq and Syria (ISIS). But those protesters may be unaware the extent to which such al-Qaeda-linked groups are sowing deadly strife among Muslims in Syria.

Fierce battles have erupted between ISIS and al-Nusra Front (ANF), with hundreds reportedly killed. Such infighting among Muslims is strictly forbidden, clerics and scholars say.

Recruits who join these groups expect to fight against the Syrian regime but often find themselves "provoked to fight against their brothers in arms, ideology and Islam", said Abdullah al-Muqrin, professor of comparative jurisprudence at Umm al-Qura University in Mecca.

Since its inception, al-Qaeda has distorted Qur'anic verses and hadiths to serve its interests, he added.

"It proceeded to spill the blood of civilians and the blood of Muslims who oppose its takfiri course," he said. "This has no relation to Islam. Rather the opposite, for the fate of he who sheds the blood of his Muslim brother is hell."

A departure from religion

Idealistic young men who want to help suffering Muslim brethren in Syria, may not know that armed extremists in that country are violating Islam by fighting among themselves.

"A Muslim is prohibited from shedding the blood of his brother Muslim," said Ramez Yahya, an Al-Azhar University sharia professor. "What al-Qaeda is doing in Syria and Iraq is a departure from religion itself."

Unversed Muslim youths are being misled by false and prejudiced fatwas, Yahya said, noting that Prophet Mohammed "ordered Muslims to break and disable their weapons so they (Muslims) do not fall into fitna (strife) and kill their Muslim brothers".

Agree, or die

Before moving to Cairo, Sheikh Maaz Abdul Karim was a preacher at al-Omar mosque in Aleppo in Syria, where he witnessed the fitna and oppression of these groups first hand.

"ISIS and ANF were able to recruit many Muslims into their ranks, some of whom are Syrian and some are migrants or foreign fighters, and were able to embroil them in the fitna, fighting and shedding Muslim blood, which God and his messenger prohibited," Abdul Karim said. "The going rule among ISIS, ANF, Ahrar ash-Sham and other groups at this time is, 'He who is not with us is against us'."

He said he and many other Syrians suffered "clear oppression at the hands of al-Qaeda-affiliated terrorist organisations".

"In the end, I preferred to leave Syria as I found myself facing two choices: either they kill me for rejecting al-Qaeda's views, or I toe the line of their views, which goes against what I was raised on and the principles of the sharia I learned."

Islam prohibits partisanship because the existence of parties leads to intolerance towards each other, he said.

"How can they say they are establishing an Islamic state, having started with false premises which are at their root far-removed from religion?" Abdul Karim asked.