How do we identify the people who are genuinely part of the Body of Christ? If we are to depend on them as the church, the pillar and foundation of the the truth, we need a way to sort out the false members from the genuine. How do we do that?
Every professing believer is a member of the body of Christ, but not every one is abiding in Him. Paul teaches us this here.
2 Thessalonians 3:1Finally, brethren, pray for us, that the word of the Lord may have free course, and be glorified, even as it is with you: 2 And that we may be delivered from unreasonable and wicked men: for all men have not faith. 3 But the Lord is faithful, who shall stablish you, and keep you from evil. 4 And we have confidence in the Lord touching you, that ye both do and will do the things which we command you. 5 And the Lord direct your hearts into the love of God, and into the patient waiting for Christ. 6 Now we command you, brethren, in the name of our Lord Jesus Christ, that ye withdraw yourselves from every brother that walketh disorderly, and not after the tradition which he received of us. 7 For yourselves know how ye ought to follow us: for we behaved not ourselves disorderly among you;..........14 And if any man obey not our word by this epistle, note that man, and have no company with him, that he may be ashamed. 15 Yet count him not as an enemy, but admonish him as a brother.
So it is about correcting error by the scripture with His help as the head of every believer is Christ aka the Word of God just as the head of the church is.
2 Timothy 3:12 Yea, and all that will live godly in Christ Jesus shall suffer persecution. 13 But evil men and seducers shall wax worse and worse, deceiving, and being deceived. 14 But continue thou in the things which thou hast learned and hast been assured of, knowing of whom thou hast learned them; 15 And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus. 16 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: 17 That the man of God may be perfect, thoroughly furnished unto all good works.
Ephesians 4:12 For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: 13 Till we all come in the unity of the faith, and of the knowledge of the Son of God, unto a perfect man, unto the measure of the stature of the fulness of Christ: 14 That we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, and cunning craftiness, whereby they lie in wait to deceive; 15 But speaking the truth in love, may grow up into him in all things, which is the head, even Christ: 16 From whom the whole body fitly joined together and compacted by that which every joint supplieth, according to the effectual working in the measure of every part, maketh increase of the body unto the edifying of itself in love.