One of the key things you can do to prevent embezzlement at your church, that most churches do not do, is to have two people opening the mail at the same time. If one person opens the mail alone, it is too easy to slip checks or cash out.
A second “best practice” is to only give credit cards to staff, and only a few. Always have a non-staff person carefully match credit card receipts to statements.
Third, and this gets disregarded a lot, the offering should not be counted by one person alone or by one family alone. There should always be two to three people from separate families counting the offering. No church is too small. In fact, small churches are very vulnerable to pilfering or even larger financial misconduct.
You can’t stop people from stealing, but if you have good internal controls, you will minimize temptation and the opportunity for theft.
For more guidelines for internal control best practices, check out this resource from churchwide, provided by the Office of the Treasurer, along with other helpful resources.