In the book of 2 John, the keyword is "truth." It is found thirteen times in theis letter. Paul wrote to a church being bombarded by Judaizing teachers (Galatians 2:4,5). He taught what truth is and how it is to be observed.
Three reasons from 2 John why truth is so important:
1) It is the means by which we receive grace, mercy and peace.
Grace - kindness; bestowing upon someone something they do not deserve.
Mercy - not receiving what a person does deserve (1` Timothy 1:12-14).
Peace - we can have peace no matter what circumsyances arise. Job found peace though he lost all that he had (Job 1:20-22). Paul found peace and contentment regardless of the trying situations he found himself in (2 Corinthians 11:23-27).2) It helps us to produce godly families.
Truth must first be taught in our homes (Deuteronomy 6:6-9). Families must "walk" in the truth (3 John 3; Matthew 5:16). Many deceivers had gone out into the world, seeking to distort the truth. The same is occurring today. People today are seeking to lead many away from the truth. Many books are written today to divert the attention away from the plain truth of the Bible. Biblical truth is also being compromised in many "Christian" universities. Wolves in sheeps clothing are filling pulpits of the Lord's church, preaching doctrine which is less than the complete and necessary truth.3) It helps us to recognize false teaching.
With the New Testament as our guide, we have the ability to know that a doctrine is either false or true. (2 John 9).
Galatians 2:4,5
4 And that because of false brethren unawares brought in, who came in privily to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage:
5 To whom we gave place by subjection, no, not for an hour; that the truth of the gospel might continue with you.1 Timothy 1:12-14
12 And I thank Christ Jesus our Lord, who hath enabled me, for that he counted me faithful, putting me into the ministry;
13 Who was before a blasphemer, and a persecutor, and injurious: but I obtained mercy, because I did it ignorantly in unbelief.
14 And the grace of our Lord was exceeding abundant with faith and love which is in Christ Jesus.Job 1:20-22
20 Then Job arose, and rent his mantle, and shaved his head, and fell down upon the ground, and worshipped,
21 And said, Naked came I out of my mother's womb, and naked shall I return thither: the LORD gave, and the LORD hath taken away; blessed be the name of the LORD.
22 In all this Job sinned not, nor charged God foolishly.2 Corinthians 11:23-27
23 Are they ministers of Christ? (I speak as a fool) I am more; in labours more abundant, in stripes above measure, in prisons more frequent, in deaths oft.
24 Of the Jews five times received I forty stripes save one.
25 Thrice was I beaten with rods, once was I stoned, thrice I suffered shipwreck, a night and a day I have been in the deep;
26 In journeyings often, in perils of waters, in perils of robbers, in perils by mine own countrymen, in perils by the heathen, in perils in the city, in perils in the wilderness, in perils in the sea, in perils among false brethren;
27 In weariness and painfulness, in watchings often, in hunger and thirst, in fastings often, in cold and nakedness.Deuteronomy 6:6-9
6 And these words, which I command thee this day, shall be in thine heart:
7 And thou shalt teach them diligently unto thy children, and shalt talk of them when thou sittest in thine house, and when thou walkest by the way, and when thou liest down, and when thou risest up.
8 And thou shalt bind them for a sign upon thine hand, and they shall be as frontlets between thine eyes.
9 And thou shalt write them upon the posts of thy house, and on thy gates.3 John 3 For I rejoiced greatly, when the brethren came and testified of the truth that is in thee, even as thou walkest in the truth.
Matthew 5:16 Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven.
2 John 9 Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son.
