The victim was identified as Sadarudin, a resident of the run-down Transito shelter in Mataram, Lombok, that has been home to almost 150 persecuted Ahmadi for the last six years.
Metro TV reported that the victim, who is deaf and mute, was collecting wood near the shelter on Wednesday when he was attacked.
Local police said that according to witnesses, the attacker attempted to behead the victim but was scared off when other Ahmadi heard the commotion, according to the report.
The victim, who would not have been able to call for help, suffered serious head injuries and is fighting for his life in the Mataram General Hospital.
It is understood the assailant had approached his intended victim and asked to borrow his machete before using it in the attack.
The Transito (transit) shelter is home to 138 members of the beleaguered sect who struggle to survive.
The electricity to the shelter was cut off more than three years ago, food aid from the government — which has perpetuated their limbo by refusing them the right to return home or register as residents — was halted last year, and sanitation facilities are non-existent.
A stipend from the state was stopped in 2007.
Not being registered residents, they have been denied the free gas stoves distributed by the government to all citizens, and they now resort to gathering scrap to burn as fuel.