Samir Mohandis, a member of the board of the East Preston Islamic College, said he suffered head injures during the attack by an unknown assailant who entered the schoolground about 4.45pm on Friday.
Police said the attacker, a man aged in his 30s, appeared to have been holding a firearm.
The assailant was not known to Mr Mohandis nor did he say anything to indicate the attack may have been racially motivated, a police spokeswoman said.
Mr Mohandis told Southern Cross Broadcasting the man claimed to be Jesus.
He said security at the school would be increased.
“I still have scars to my head,” he said.
The attacker is described as being about 180cm tall and of muscular build with a tattoo on his right forearm.
He had straight dark brown hair and at the time of the incident was wearing a grey t-shirt and dark trousers.
Anyone who may have seen the man in the vicinity of the school around the time of the incident should call Crime Stoppers on 1800 333 000.
Two Muslim students were expelled from East Preston College earlier this month for urinating and spitting on a Bible and then setting it alight.
At the time, the college head, Shaheem Doutie, said the incident was isolated and the school had done all it could to punish the people involved.
We appreciate your support
Our website includes affiliate links, which means we get a small commission — at no additional cost to you — for each qualifying purpose. For instance, as an Amazon Associate Religion News Blog earns from qualifying purchases. That is one reason why we can provide this service free of charge.