Thirty churches in countries like the United States, Spain and India are using Churchix, which matches the faces it sees on CCTV footage with photographs and personal information already put into a database.
By linking what it sees in real-time with the photographs, it can tell who is and isn't attending services.
The biggest church using Churchix at the moment has a congregation of around 10,000. No churches in Britain currently use the technology.
Face-Six, a company in Israel, makes the Churchix software. It's CEO, Moshe Greenshpan, told The Times newspaper: "I understand when people say it's spy software and it intrudes [on] privacy but it's not really like that.
"It's for ease of use of the church to keep track of people automatically."
However Mal Fletcher, a social futurist, told Premier's News Hour: "When it comes to facial recognition I do have some concerns. One is that it can so easily be used without the knowledge or permission of churchgoers or visitors.
"Even if a regular churchgoer says 'yes, you can take my picture while I'm in church', the same cameras are trained on people who may be visiting for the first time; they might even be unaware they're being photographed.
"I think churches should be leading the call for greater protections of privacy... What happens with the data once it's collected? How can a church guarantee that the information remains secure, that it's not going to find its way into the hands of less scrupulous people who might use it for ID theft and the like?
"I mean, governments can't even make that guarantee any more, how can a church do it?
"If we introduce facial recognition as the start of the process, what's to stop the rest of follow-up becoming automated as well, so that people are getting automated emails and phone messages under the guise of follow-up, and it's not really follow up at all?
"I think churches rightly preach that individuals count. They should uphold that belief by treading very carefully when it comes to infringements of privacy."
Listen to Premier's Marcus Jones speaking to Mal Fletcher on the News Hour:
