The man, now in his 60s, was sentenced to 18 months in prison, with release conditions to not associate with his victim or any person under 16 without an informed adult supervisor approved by a probation officer.
He was also placed on the Child Sex Offender Register.
Defence counsel Stephen Yee, who cited reports which raised issues about the man's own previous trauma, argued for a sentence of home detention.
But Crown counsel Lara Marshall said the offending had been very serious, ongoing, involved a breach of trust and required the condemnation of the court.
Judge Rea said home detention was not appropriate.
"This is repeated and regular offending against a vulnerable young child," the judge said.
Judge Rea said the man had "embraced religion" and had a strong faith, but "your moral compass was not such that it stopped you from offending over this time".
Marshall said the man had been active in his church community but had not been allowed to attend since his offending came to light.
The court was told the man had a limited criminal history and no similar previous offences.