I doubt most religious institutions are short on cash, but here's a snippet of an official explanation
Source: https://www.acnc.gov.au/for-charities/start-charity/not-profitMaking a profit
A not-for-profit can make a profit, but any profit made must be used for its purposes. It can keep profits as long as there is a genuine reason for this and it is to do with its purpose. For example, a good reason to keep profits may be to save up for a new project, new infrastructure or a building, or to accumulate a reserve so it can continue to be sustainable.
If an organisation continues to hold onto significant profits indefinitely, without using them for its charitable purpose, this may suggest that the organisation is not working solely towards its stated charitable purpose (and is not operating as a not-for-profit).
