An associate of convicted hate preacher Anjem Choudary has been found guilty of knocking a boy unconscious as he was cuddling a girl.
Michael Coe, 35, saw the two 16-year-olds hugging in east London and demanded to know if they were Muslims.
Southwark Crown Court heard the Muslim convert then called the girl a "whore", before throwing the boy to the ground.
Coe, who left the boy unconscious and bleeding after he kicked his head, was found guilty of assault and battery.
The married father-of-two had previously admitted "shoving" the boy, who is half his size, but said he was acting in self defence.
The attack happened on 15 April as Coe was driving along Wilson Road in Newham.
The court heard that passing schoolteacher Boutho Siwela tried to come to the teenager's aid, but Coe then attacked him as well.
Judge Michael Gledhill described Coe as a danger to the public and said he would face a "substantial" term of imprisonment when he is sentenced on 21 September.
Radicalised in prison
The court heard that Coe was convicted of a similar offence in May 2013 when he confronted teenagers about their "inappropriate language".
He also has a long record of violent offences starting when he was 16, including assaults, burglary, robbery and violent disorder.
While serving an eight-year term in 2007 for firing a shotgun at police during an arrest, he was radicalised in prison by Al-Qaeda terrorist Dhiren Barot.
Coe, since known as Mikaeel Ibrahim, became a close associate of Choudary when he joined the banned organisation Al-Muhajiroun.
In November 2014, he was jailed for 15 months after being found in a lorry with false ID documents in Dover, Kent.
Coe was accused of plotting to travel to Syria to join IS but was acquitted of engaging in conduct in preparation of terrorist acts.