former redgum frontman john schumann has slammed anti-islam protesters for using his song , i was only 19 , at one of saturday 's reclaim australia rallies .
the songwriter , who penned the 1983 anthem , said the song - like many of his others - was about compassion , tolerance and inclusiveness .
but it has emerged the hit was played at one of the rallies , which aimed to oppose sharia law , halal tax and islamisation ' .