Apparently “banks train tellers to spot counterfeits by over-exposing them to real money so that when a fake one comes across they can spot it right away; not because they have been studying and dwelling on the false, but because they know the truth so well” (Thanks Clay!)
Hearts and lungs
When I told my wife this, she remembered that her medical school professors insisted that she listen to the chest of every single person she examined, even though there was no suspicion of a lung or heart problem. Why? Because only by listening to thousands of healthy chests would she be able to spot the diseased lungs and hearts when they came along.
Over-exposure to truth
In my early ministry I tended to spend a lot of time highlighting and condemning errors of all stripes and sizes. But while exposing evil is sometimes necessary, I now believe that that vast majority of preaching should be to ”over-expose” people to the truth. That not only builds and strengthens faith, it’s also a far better way of preparing people to detect and avoid falsehood.
The principle also applies to pastoring. Some pastors don’t regularly visit with their flock; instead, they wait until problems arise before they get involved. However, unless we are regularly listening to lots of spiritually healthy hearts and lungs, we’re going to miss unhealthy ones as well, with potentially fatal consequences. Regular pastoral visitation grows and sensitizes our pastoral antennae, and develops in us an uncanny ability to detect spiritual malaise before it is too late.