The couple’s religious beliefs will form part of the police investigation into the alleged murder.
Police were called to the semirural home about 6.45am on Thursday and found the body of the infant.
Inner West Crime Group Detective Inspector David Jackman said the child appeared to have suffered “visible” injuries.
“I’ve been a detective for 30-odd years and it’s one of the most confronting scenes that I’ve seen.”
Jackman said the three were known to each other and lived at the home.
A crime scene has been declared and Operation Uniform Salwood established to investigate the circumstances of the boy’s death.
“Both the man and woman are not known to police, neither is that address,” he said.
“The investigation has uncovered injuries to the child that are enough for us to charge [the pair] with murder.
“The circumstances leading to the death we will allege have happened in the last 24 hours.
“From what I have seen the child wasn’t neglected in terms of nourishment and such, but it’s quite confronting.”
Police will allege at least one of the pair had a reckless indifference to the baby’s life, Jackman said.
It is not known whether the baby had any underlying health issues.
Nothing untoward had been uncovered by police in the semirural area.
Jackman told reporters the man and woman were very upset when they were taken into police custody.
“At this stage, we will be going back through family history, speaking with family and seeing if they were aware of anything that may have led to this,” he said.
The pair are expected to face Brisbane Magistrates Court on Monday.
