People who regularly attend church (or synagogue, mosque etc) are likely to be more influenced by religion than those with only a nominal religious affiliation. On the theory that most religions tend towards cultural conservatism, I’d expect frequent churchgoers to be more likely to support the Coalition than Labor.
The figure below, which looks at people who say they attend a religious service once a week or more, confirms this hypothesis. The more interesting aspect of it is that there appears to be almost no trend in this over 40 years.
If we put the 1967 Labor result down to the complexity of dealing with the DLP in that year (broken down results: 30% Labor, 9% DLP), and put the 1990 Coalition result down to some rogue factors, we have virtually flat lines over four decades.
Given all that’s been going on in changing religious observance, along with wider social and political changes, this aspect of religion and politics seems extraordinarily stable.