Come-to-Jesus meeting

A 'come-to-Jesus' meeting is a meeting or talk where someone in power tells someone else what mistakes they're making and how they need to change. This expression most likely originated with the idea that traditional Christians have that Jesus came to earth to show people the error of their ways so they could change and be saved. Nonetheless, the expression is now used by the religious and non-religious alike, as a way to express that someone needs to have a talk with someone else before things get worse.

Example:
-I'm worried about my son. His grades are really slipping.
-Maybe it's time you had a come-to-Jesus meeting with him.