The sadistic California couple who kept their 13 malnourished children captive in their squalid suburban home believed that their massive brood came from a higher calling, the victims’ grandparents said.

David and Louise Turpin thought that “God called on them” to pump out so many children, David’s parents, James and Betty Turpin, told ABC News.

Authorities said Monday that the couple habitually abused their own progeny — ages 2 to 29 — by withholding food and keeping them shackled inside their dark and filthy Perris, Calif., home after a 17-year-old daughter escaped the hellhole the day before.

The couple practiced Pentecostal Christianity but they did not have a local church, according to James and Betty.

The evangelical sect puts emphasis on direct, personal experiences with God, and adherents are known to speak in tongues or practice scientifically discredited “faith healing.”

David and Louise were arrested on torture and child endangerment charges and are being held on $9 million bail each, according to authorities.