Bishop Mar Mari Emmanuel sustained lacerations to his head after a knife-wielding attacker repeatedly lunged at him during a live-streamed sermon at Christ the Good Shepherd Church in Wakeley on Monday night.

Police are treating the knife attack as a terrorist act carried out by a 16-year-old boy who allegedly made comments in Arabic that referred to insults against "my Prophet" before the stabbing.

The conservative Assyrian church leader is known for his outspoken views against COVID-19 lockdowns, homosexuality and non-Christian religions, including Judaism and Islam.

Many of his sermons, broadcast to up to 240,000 followers, have criticised the Koran and the teachings of the Prophet Mohammed.

In a December 2023 episode of a US podcast, Bishop Emmanuel declared: "Jesus Christ is the only God."

"Let me ask you my dear Muslim, if you are claiming Isa (Jesus) as a prophet, then how come all the other prophets you believe in ... how come none of the Old Testament prophets were referred to as the son of God," he said.

In another sermon reposted to YouTube, the bishop gave his views on the Koran, stating: "You want me to believe in a document that came seven centuries after the Holy Bible."

Australian Catholic University head of theology Joel Hodge said many in the local Assyrian community continued to feel the wounds of oppression.

Assyrians - an almost entirely Christian minority group native to an area that spans parts of modern-day Iraq, Syria, Iran and Turkey - have faced persecution as a religious and ethnic minority distinct from the region's Arab and Muslim majorities.

"They're a strong community bounded by that identity," Dr Hodge told AAP.

"Western Sydney is an absolute melting pot for different cultures from the Middle East where there are often complicated relationships between various groups."

Dr Hodge said Bishop Emmanuel had developed a reputation for "various political statements made" but he didn't believe this especially marked out the religious leader.

Deakin University extremism expert Josh Roose said the current online environment, particularly in the context of the Israel-Palestine conflict, had heightened tensions between various groups.

"(It's) created a fertile environment for individuals who are angry, who are looking to act out, to target, to be inspired and to go and target someone," he said.

Religious groups have since spoken out against the attack and called for calm.

The Lebanese Muslim Association said it "rejects violence in all its forms" and hoped the attack would not undo 20 years of inter-religious progress.

"We condemn it outright," secretary Gamel Kheir said.

"It has no place in religion, it has no place in this society."

Australian Associated Press