If anyone comes to you and does not bring this doctrine, do not receive him into your house nor greet him; for he who greets him shares in his evil deeds – 2 John 1:10-11
I ignored this warning years ago living in the suburbs north of Seattle. Two Mormon missionaries knocked on my door, and I did something I instinctively and Biblically knew I shouldn’t do: Let them in. I thought I would share the gospel with these young men. My presentation was brief but not received. Before they left my 2-year-old daughter wandered over and one of the Mormons bent down and touched her stomach with his finger. An hour later she was throwing up. I don’t believe this young man meant any harm but my first thought was: did this LDS missionary have a demon that attacked my kid?
I felt bad for obvious reasons. I hadn’t obeyed Scripture nor protected myself and family. From that point whenever Mormon and Jehovah Witness missionaries came to my door I’d say politely I’m not interested, and close the door. Then pray for them.
Baptist preacher A.T. Robertson addresses the seriousness of the 2 John passage above in his New Testament Commentary:
John does not refer to entertaining strangers (Heb. 13:2; 1 Tim. 5:10), but to the deceiving propagandists who were carrying dissension and danger with them. . . . It can very well be understood of the peril of allowing these Gnostic propagandists to spread their pernicious teachings (cf. Mormons or Communists) in home and church (usually meeting in the home). This is assuming that the men were known and not mere strangers.