Before we begin to explain how to deal with offensive people calling themselves Christians, we need to learn how to identify them. Church-goers often accuse their others of being offensive when they're just telling telling the truth, and we need to keep in mind that telling the truth is not a condemned offense in the Bible.
And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved.
-2 Thessalonians 2:10
The first thing we ought to do, when a saved Christian comes to us with an accusation, is examine ourselves.
Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?
-2 Corinthians 13:5
Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth.
-2 Timothy 2:15
There are disputable matters in which two Christians can disagree, and both still be correct; for example, one eats meat and the other does not, or one honors the sabbath and the other does not. If a Christian brings to dispute a matter that is at liberty to be based on personal conviction, both positions can be correct, however, it is not as common today as the other three possibilities.
We need to understand that Christians are still men and women in the flesh, and though we put on the Lord Jesus Christ for Salvation from wrath, and He sends the Holy Spirit to us for guidance, we are not perfect. Sometimes, we need rebuke to tell us when we have crossed a line, or not observed certain Scripture concerning our actions/words, and we rebuke so that the Body of Christ will be sound in the faith.
This witness is true. Wherefore rebuke them sharply, that they may be sound in the faith;
A wise son heareth his father's instruction: but a scorner heareth not rebuke.
scorn (v): to hold in extreme contempt; to despise; to condemn; to disdain; to consider another without worth; to neglect
(See 'scorn', Noah Webster's Dicitonary, 1828, retrieved Jan 20, 2014, [webstersdictionary1828.com])
Take heed to yourselves: If thy brother trespass against thee, rebuke him; and if he repent, forgive him. And if he trespass against thee seven times in a day, and seven times in a day turn again to thee, saying, I repent; thou shalt forgive him.
As a Christian, we ought to be at least willing to hear what our Christian brethren have to say to us. On the flip side, we should also be willing to approach someone in a meek and reasonable manner.
And the servant of the Lord must not strive; but be gentle unto all men, apt to teach, patient, In meekness instructing those that oppose themselves; if God peradventure will give them repentance to the acknowledging of the truth; And that they may recover themselves out of the snare of the devil, who are taken captive by him at his will.
-2 Timothy 2:24-26
strive (v): To contend; to contest; to struggle in opposition to another; to be in contention or dispute
(See 'strive', Noah Webster's Dicitonary, 1828, retrieved Jan 20, 2014, [webstersdictionary1828.com])
One of the easiest ways to identify a contentious Christian is whether or not they rail.
rail (v): To utter reproaches; to scoff; to use insolent and reproachful language; to reproach or censure in opprobrious terms
(See 'rail', Noah Webster's Dicitonary, 1828, retrieved Jan 20, 2014, [webstersdictionary1828.com])
And he said unto them, Ye are they which justify yourselves before men; but God knoweth your hearts: for that which is highly esteemed among men is abomination in the sight of God.
Help, LORD; for the godly man ceaseth; for the faithful fail from among the children of men. They speak vanity every one with his neighbour: with flattering lips and with a double heart do they speak.
See that none render evil for evil unto any man; but ever follow that which is good, both among yourselves, and to all men.
-1 Thessalonians 5:15
Not rendering evil for evil, or railing for railing: but contrariwise blessing; knowing that ye are thereunto called, that ye should inherit a blessing.
-1 Peter 3:9
Christians should be longsuffering, which means we take the brunt of insults and attacks from others, but we remain patient. Next, we mark them and avoid them.
Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them. For they that are such serve not our Lord Jesus Christ, but their own belly; and by good words and fair speeches deceive the hearts of the simple.
mark (v): To notice; to take particular observation of; to observe critically
(See 'mark', Noah Webster's Dicitonary, 1828, retrieved Jan 20, 2014, [webstersdictionary1828.com])
(If you don't understand how Jesus Christ taught that division brings peace, read "Did Christ Come to Bring Peace?" here at creationliberty.com for more details.)
Most Christians are not used to hearing these things preached in sermons today, and few are willing to do what it takes to do right by God's Word in this matter. If Christians are openly doing the works of the flesh, in their actions and speech, then we ought not to even sit down and have a meal with them, and Paul "beseeched," or urged, Christians to mark and avoid them.
But now I have written unto you not to keep company, if any man that is called a brother be a fornicator, or covetous, or an idolater, or a railer, or a drunkard, or an extortioner; with such an one no not to eat. For what have I to do to judge them also that are without? do not ye judge them that are within? But them that are without God judgeth. Therefore put away from among yourselves that wicked person.
-1 Corinthians 5:11-13
Because our associations will end up influencing us.
The people we hang out with can influence our behavior. If we spend time with someone who likes to get drunk, it doesn't matter how long it takes, eventually, he can influence us to join in with him. So many Christians believe they are immune to certain actions, and that nothing bad will happen, but that's not what the Bible says:
Your glorying is not good. Know ye not that a little leaven leaveneth the whole lump?
-1 Corinthians 5:7
Notice, it does not say we avoid those we have a disagreement with. Just because a Christian might disagree with me, does not mean I avoid them or cast them out. However, many Christians are selfishly and pridefully abandoning/condemning other Christians over minor disagreements. I've seen a pastor tell a Christian man that the Holy Spirit sent the pastor to help him, but when the man refused to become a member of his church congregation, the pastor abandoned him and never spoke to him again. There's no Biblical justification for that. (Not to mention lying about the Holy Spirit!) It is sickening to watch Christians abuse their liberty in Christ over selfish motivations, instead of putting emphasis on truth and righteousness of the Gospel.
This doesn't mean we mark and avoid every person on the planet:
I wrote unto you in an epistle not to company with fornicators: Yet not altogether with the fornicators of this world, or with the covetous, or extortioners, or with idolaters; for then must ye needs go out of the world.
-1 Corinthians 5:9-10
Let's say we're all in a church congregation together, and you find out someone is doing something wrong. How do you handle it? Do you go to the pastor and let him take care of it? No. The Bible gives instructions on how to handle these situations:
Moreover if thy brother shall trespass against thee,
Assuming he is not railing, I typically like to start out by quoting Scripture to another Christian and then asking him questions. This helps keep me from assuming too much without first seeking understanding of his position via his answers. This also helps me to verify if I am Biblically sound in what I'm saying, and we should never immediately approach a situation assuming we are automatically correct; we have to examine ourselves first. (2Cr 13:5) Then, based on his answers, I can see if he is a Christian that can be talked to and reasoned with, or if we are dealing with a scorner.
If he can't be talked to or reasoned with, then get two or three witnesses to establish every word. What if they were right all along and we are the ones not on the proper Scriptural foundation? What if we were judging hypocritically? This is why Christian witnesses to these conflicts are so important. The witnesses and the congregation will help to determine the truth of the matter and will peacefully give both parties equal opportunity to repent and reconcile.
It is not always fun to mark offenses and divisions, and most Christians are too scared to approach others, but it is necessary to make sure we are all on the same path of faith and righteousness, anchored by our our Lord Jesus Christ, protected from evil works of iniquity. I have had numerous letters from Christians talking about how their church leadership has done something wrong, and often, we end up discussing the difficulties in approaching them Biblically. Most of the time, in one-on-one conversation, the church leader will excuse away his offenses, and any further steps from Matthew 18 end up in the Christian having to leave the congregation to get away from lies and gossip. I'm not saying that Christians coming forward to others always ends up bad, but most of the conversations I've had with Christians on this matter have ended poorly in sin, instead of edification and reconciliation to God's Word. (And that's what sparked me to write about this issue.)
Things may not always go as peacefully as planned, but if you approach someone in a peaceful manner with proper backing from God's Word, then you do not need to be ashamed in approaching any Christian:
Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth. But shun profane and vain babblings: for they will increase unto more ungodliness.
-2 Timothy 2:16
The heart is deceitful above all things, and desperately wicked: who can know it?
And whosoever shall not receive you, nor hear your words, when ye depart out of that house or city, shake off the dust of your feet.
In the end, though we have some responsbilities towards our Christian brethren, we are not responsible FOR them. Each of us is responsible for our own actions and words, and will be judged accordingly by them.
But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment.
These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the scriptures daily, whether those things were so.
Prove all things; hold fast that which is good.
-1 Thessalonians 5:21
And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
If Christian brethren won't speak with you, rails on you, or will not hear you, then it's best to just take your hands off it and let it go.