2 John (only one chapter):

v5-6: John emphasizes the importance of having love for others which indicates we are obeying Jesus’ commandments.

v7: He gives a warning concerning a deceptive philosophy called gnosticism. This contends that Jesus was only a spirit and that He did not consist of flesh and blood. It also asserts that secret knowledge must be discovered to have Truth. Because this whole mindset substitutes for the real Jesus Christ, John called the spirit behind it “antichrist.” The prefix “anti” does not only mean “against.” It also means “in place of.” Therefore, an antichrist is someone who is in place of the real Jesus, or claims to be all that Jesus is and has people treat them as such. Surprisingly, the word antichrist is never mentioned in the entire Book of Revelation, but certainly antichrist activities are described there. More on this in my commentary on Daniel and Revelation.

v9-10: A person who does not abide in the teachings of Christ does not have God and should not be greeted or be received into our house. Does this mean cults knocking at our door should not be invited in to our house to talk? Some Christians believe so. Others think these verses mean something else. In New Testament times, teachers and preachers did not necessarily get many invites to speak in Jewish Temples on Saturdays, nor were there any church buildings yet. So many went from house to house and town to town. People were given a platform from which to teach from within someone’s house. Some interpretations suggest that we should not allow cultists in our homes “to give them a platform” for their propaganda, but to share the real Christ with them is okay to do.

I’ve personally had a lot of experience with Mormons and Jehovah’s Witnesses. I am not sure what these two verses mean, so I can only make some suggestions. For new Christians, I do not think it is good to engage with any cultist until you know the Scriptures well. Pray for them but do not talk doctrine with them. If you know the Scriptures well, certainly pray for them when you see them in your neighborhood, and pray against the spirit of error so that it has no impact in your area. In general, I do not think it is a good idea to engage them. The Spirit, however, may make exceptions so we must be sensitive to what He is saying at the time.

One day two Jehovah’s Witnesses came to my front door. They wanted to come in. So I said under one condition. They asked, what condition. As they were stepping forward (thinking that there is no condition that would prevent them form entering my house), I said, “That we speak ONLY of Jesus Christ.” Their front feet stopped in mid air and then retracted. They would not come in. Amazing. If someone said that to me, I’d be in that house in a flash! But this reveals the demonic spirit of error that these groups have. On a more recent occasion, they came when I was doing yard work. As they talked, my mind became confused and fear of not knowing what to say engulfed me. I began to pray in the spirit (silently to God) for that fear to turn on them and it instantly left me. The long-time Witness’ lip started quivering suddenly, and he became confused and less confident. God just turned the “spiritual tables” around. So for new Christians I do not advise them to engage the cultists. Scriptural debates will go on endlessly to no avail. It is not a matter of Bible knowledge alone. It is a battle against demonic strongholds.