Do you let just anybody in your house? Do you allow the thief and rabble-rouser to disturb your peace? Don’t we install locks and alarms to keep out the people who would harm us? And what about the church?
Watch out, so that you do not lose the things we have worked for, but receive a full reward.
2 John 8 NET
The main verb here is literally “to see.” Look! This subject requires full attention, in order that it may be dealt with properly.
By receiving false teachers and giving them space to win converts in the Christian community, the disciples would destroy the work of Christ done by the apostles and preachers.
They should shut the doors to the false teachers. “Do not receive him into your house” (verse 10).
In God’s church, there is no freedom of expression. We have freedom to speak the words of Christ. And nothing more.