Q: In 2 Jn 1 and 3 Jn 1, how do we know that John the apostle wrote 2 John and 3 John?
A: The books do not say who wrote them, but John in his Gospel and 1 John was reluctant to use his name. The early church never questioned that these were by John, and 2 and 3 John have a similar style to 1 John and the Gospel of John.
 

Q: In 2 Jn 1, 5, who is the elect lady?
A: There are two theories on the identity of the elect lady.
A Particular Lady: A particular, but now unknown, lady in the early church.
Allegorical: The church in general. The church is called the bride of Christ in John 3:29; Revelation 21:2,9; 22:17; and Ephesians 5:25-33.
While John uses the plural "you in 2 John 8 and asking people to love one another in 2 John 5, the letter was actually not just to a lady, but to a lady and her children. See When Critics Ask p.543-544 and Hard Sayings of the Bible p.745-746 for more info.
 

Q: In 2 Jn 7, who is John addressing as not believing "Jesus came in the flesh"?
A: Two groups of people later emerged as denying Jesus coming "in the flesh". They taught that Jesus was similar to phantom, who just appeared to have a physical body.
Proto-Gnostics, including believed that salvation was through secret, mysterious knowledge, the physical world was bad, and Jesus was a phantom. See the discussion on 1 John 1 "Who were the Gnostics" for a little more info. For a lot more info, see Tertullian’s Against Marcion (204 pages 207 A.D.), Hippolytus’ Refutation of All Heresies (222-235/6 A.D.), Irenaeus’ Against Heresies (written about 182-188 A.D.), and Clement of Alexandria Stromata (wrote 192-217/220 A.D.) See Hard Sayings of the Bible p.746-748 for more info on this question.
Docetists were others who denied that Jesus was coming in the flesh.
For both groups, the origin of this idea likely was from Greek philosophy, which taught that matter was impure. If Jesus was perfect and sinless, Jesus could not have a body of matter, or so their philosophy went.
 

Q: In 2 Jn 7 and 1 Jn 2:18,22, is the Antichrist a person?
A: Yes. While there is also a spirit of the Antichrist, the Antichrist is a person who claims "I am He" and deceive people as a false Christ as Matthew 24:23-24 shows.
 

Q: In 2 Jn 7 and 1 Jn 2:18,22, are there many antichrists, or is there just one?
A: There is only one primary Antichrist according to Matthew 24:4-5,26; Mark 13:6,14; Luke 21:8; Daniel 9:26-27, 11:36-37; 2 Thessalonians 2:3-4; and Revelation 13:1-10. However, there are many lesser antichrists as 1 John 2:18,22 and 2 John 7 show. There might be a relationship between someone having the spirit of the antichrist in them (1 John 4:3), and what psychologists describe as a Messiah complex.
Here is a partial list of people who have claimed to be a Messiah.
 

…Christ returned

Grigori Rasputin (at least some others claimed this)

Rev. Jim Jones of Jonestown (died 11/16/1978)

Rev. Moon of the Unification Church

Jacob Katzan (1977-)

Guru Maharah Ji of the Divine Light Mission

many Hindu and New Age gurus

…A Jewish Messiah Come the First Time

Sabbatai Sebi/Zvi In Sept. 1666 A.D. he was forced to become Muslim

Rabbi Schneerson of New York (now dead)

probably Theudas in Acts 5:36. He claimed to be someone great

…The Mahdi in Shi’ite Religions

Imam al Husayn bin al-Kasim al-‘Iyani (1010-1013 A.D.) (Husayniiya Zaydite sect)

First Fatimid caliph ‘Obaidallah/‘Ubaydullah (909-933/934 A.D.)

The Baha’ullah (Baha’is) (1817-1892)

Husayn ‘Ali Nuri Baha’, half-brother to the Baha’ullah

Sliman Murshad of Syria (1900-1949)

The Mahdist movement in Sudan

Mirza Ghulam Ahmad (1879, Ahmadiyya Movement)

many others

…Visible God

Lord Hakim (The Druze)

‘Ali is divine according to the ‘Ulyaniyya/’Alaya’iyya

Mohammed is worshipped as visible God by Muhammidiyya

‘Ali bin Abi Talib and Saliman al-Farisi (They did not claim to be God, but long after their death some ‘Alewite sects worshipped them as sort of a Muslim Tritheism.

God existed in the form of all the prophets according to the Rizamiyya / Muslimiyya Shi’ite sect

 
Here is a partial list of individuals others have called the Antichrist.

Emperor Nero

John F. Kennedy

Benito Mussolini

Josef Stalin

Adolf Hitler

Prince George (American Revolutionary War)

Various popes

 

Q: In 2 Jn 8, how can Christians lose what they have worked for?
A: While God can take away material belongings from Christians, earthly possessions are insignificant compared to the Heavenly rewards John is talking about here. We do not work for our salvation, but we do receive rewards in Heaven for our work (1 Corinthians 3:13-15). We can lose those according to 2 John 8.
 

Q: In 2 Jn 10, what does this refer to?
A: There are two main views.
Home hospitality: The most common view is that these false teachers should not be welcome in our homes. While Christians are to be hospitable in general, our homes and hospitality are not to give aid to propagating false teaching.
Church hospitality: Since churches primarily met in homes until Christianity was legalized, this refers to two things:
1. Specifically, not welcoming traveling false teachers into house churches, and
2. More generally, not giving cultists a platform to preach false doctrine. See Hard Sayings of the Bible p.748-749 and When Cultists Ask p.301-302 for more info on this view.
Hank Hanegraff of CRI in the 2/4/2004 electronic newsletter likewise says that this means not letting them in house churches where they can spread their heresies. He agrees there is also a second possible interpretation of not giving them hospitality in your home. Hank says this does not exclude allowing a cultist in your home to refute their teaching and share the gospel with them.
 
 

Q: In 2 Jn 10, should we ever welcome non-Christians into our homes?
A: Sure, Christians are to practice hospitality. Romans 12:13 and 1 Timothy 5:10 tell us to practice hospitality without qualifying this to be only for other Christians. However, 2 John 10, (really 2 John 9-11) says that people who "run ahead" and do not continue in the teaching of Christ are not to be welcomed in houses. Two points.
1. Who are they? Those who run ahead are those who intellectually heard the teaching of Christ, but did not continue and now teach something different. These people include apostates from Christianity and many cultists.
2. What are we to do? We are not to take them into our homes or welcome them. While some translations say "your houses", "your is not found in the Greek. The prohibition is both for house churches and our own homes. This is consistent with 1 Corinthians 4:11-13, which says we are not to associate with any who call themselves a brother but who lives an ungodly life.
See also the previous question.
 

Q: In 2 Jn 10, should we ever welcome cultists into our homes?
A: Genuine Christians disagree on this.
No: Many, including an ex-Jehovah’s Witness named William Schnell, say that obedience to this verse means never to let them in. Letting them in implies a desire to learn from them. William Schnell wrote this in How to Witness to a Jehovah’s Witness.
Yes, under certain circumstances: The point of the verse was to never give them the impression that we respect their soul-perishing heresy. For the purpose of sharing the Gospel with them it is OK as long as we make it clear we do not endorse or approve of their views. See The Complete Book of Bible Answers p.322-323 for more on this second view.
 

Q: in 2 Jn 10 are we not to let false teachers into our homes, or are we to love our enemies as Matthew 5:44 says?
A: Both. Giving someone the impression that their soul-perishing error is OK is one of the most unloving things you can do for that person. Loving someone does not simply mean acting soft regardless of the circumstances, but sometimes it includes caring enough to have tough love.
See both Bible Difficulties and Seeming Contradictions p.246 and When Critics Ask p.544-545 for a second, different answer.
 

Q: In 2 Jn, how do we know if what we have today is a reliable preservation of what was originally written?
A: There are at least three reasons.
1. God promised to preserve His word in Isaiah 55:10-11; Isaiah 59:21; Isaiah 40:6-8; 1 Peter 1:24-25; Matthew 24:35.
2. Evidence of the early church. Here are a few of the writers who referred to verses in 2 John.
Irenaeus wrote 182-188 A.D. refers to 4 verses in 2 John
After Nicea
Athanasius (367 A.D.) lists the books of the New Testament in Festal Letter 39 p.552
Hilary wrote about 355-367/368 A.D.
The Muratorian Canon (c.170 A.D.) mentions 2 John
3. Earliest manuscripts we have of 2 John show there are small manuscript variations, but zero theologically significant errors.
p74 (=Bodmer 17) Acts 1:2-5,7-11,13-15,18-19,22-25; 2:2-4; 2:6-3:26; 4:2-6,8-27; 4:29-27:25; 27:27-28:31; James 1:1-6,8-19,21-23,25,27; 2:1-3,5-15; 18-22, 25-26; 3:1,5-6,10-12,14,17-18; 4:8,11-14; 5:1-3,7-9,12-14,19-20; 1 Peter 1:1-2,7-8,13,19-20,25; 2:6-7,11-12,18,24; 3:4-5; 2 Peter 2:21; 3:4,11,16; 1 John 1:1,6; 2:1-2,7,13-14,18-19,25-26; 3:1-2,8,14,19-20; 4:1,6-7,12,16-17;5:3-4,9-10,17; 2 John 1,6-7,13; 3 John 6,12; Jude 3,7,12,18,24 (7th century)
7th century - 1968 - The Text of the New Testament has James 2:4 and 1 Peter 1:12
7th century - 1975 - Aland et al. Third Edition
6th century - 1998 - Aland et al. Fourth Revised Edition
Uncial 0232 c.300 A.D. according to The Complete Text of the Earliest New Testament Manuscripts (Aland considers it 5th or 6th century) 2 John 1-9
Vaticanus (325-350 A.D.), Sinaiticus (340-350 A.D.), and Alexandrinus (c.450 A.D) have all of 2 John.
Bohairic Coptic 3rd/4th century
Sahidic Coptic 3rd/4rth century
Armenian [Arm] from 5th century
Georgian [Geo] from 5th century
Ethiopic [Eth] from c.500 A.D.
 
See www.BibleQuery.org/2jnMss.htm for more on early manuscripts of 2 John.