Reuben Evans, 71, claimed to be the leader of a group he called Eternity and told the victim she was "a chosen one", a court heard.
A 42-year-old woman and a 49-year-old man were also jailed for their involvement in the sexual abuse.
At Shrewsbury Crown Court last week Milinia Eden was jailed for 10 years and Paul Evans, of Craven Arms, for two years and four months.
Reuben Evans and Paul Evans had both pleaded guilty to a number of charges relating to sexual activity with a child.
Eden had denied five allegations of sexual abuse, but was found guilty following a four-day trial.
The offences are all said to have been committed in the Cleobury Mortimer area where Eden and Reuben Evans lived.
The court heard that the victim, who cannot be named for legal reasons, had been told by Reuben Evans that "the devil would be after her".
In May 2012, the victim, having been warned she would be "killed within 24 hours" if she failed to submit to the abuse, told a relative about the abuse and the police were alerted.