“Do not receive him into your home”
If anyone comes to you but does not bring this teaching, do not receive him into your home or even greet him. (2 John 1:10 BSB)
What it sounds like today
A surprisingly cold command to be inhospitable and rude.
The cultural key
This sounds harsh until you see how the early mission worked. Traveling teachers relied entirely on believers' homes for lodging and support, since there were no inns for such work; to house, feed, and publicly greet a teacher was to endorse him and fund his message (the flip side is praised in 3 John). The 'greeting' was not a mere hello but a public blessing that signaled association and approval. So refusing hospitality to a teacher who denied Christ was not personal rudeness but withholding sponsorship of dangerous error, cutting off the platform and the funding.
Recovered meaning
To host and greet a traveling teacher was to bankroll and bless his message. John tells the church not to underwrite those who deny Christ, a refusal of endorsement, not of ordinary human kindness.