What is truth? It is the Word of God, not the words of men or the doctrines developed by other churches. Any other churches.
Sanctify them in the truth; thy word is truth.
CHRIST BUILT ONLY ONE CHURCH MATTHEW 16:18
"And I say also unto thee, that thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it."
Endeavouring to keep the unity of the Spirit in the bond of peace. There is one body and one Spirit, just as you were called to the one hope that belongs to your call, one Lord, one faith, one baptism, one God and Father of us all, who is above all and through all and in all. But grace was given to each of us according to the measure of Christ's gift. Therefore it is said, "When he ascended on high he led a host of captives, and he gave gifts to men." (In saying, "He ascended," what does it mean but that he had also descended into the lower parts of the earth? He who descended is he who also ascended far above all the heavens, that he might fill all things.) And his gifts were that some should be apostles, some prophets, some evangelists, some pastors and teachers, to equip the saints for the work of ministry, for building up the body of Christ, until we all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fulness of Christ; so that we may no longer be children, tossed to and fro and carried about with every wind of doctrine, by the cunning of men, by their craftiness in deceitful wiles. Rather, speaking the truth in love, we are to grow up in every way into him who is the head, into Christ, from whom the whole body, joined and knit together by every joint with which it is supplied, when each part is working properly, makes bodily growth and upbuilds itself in love.
For he has made known to us in all wisdom and insight the mystery of his will, according to his purpose which he set forth in Christ as a plan for the fulness of time, to unite all things in him, things in heaven and things on earth. In him, according to the purpose of him who accomplishes all things according to the counsel of his will, we who first hoped in Christ have been destined and appointed to live for the praise of his glory. In him you also, who have heard the word of truth, the gospel of your salvation, and have believed in him, were sealed with the promised Holy Spirit, which is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory. For this reason, because I have heard of your faith in the Lord Jesus and your love toward all the saints, I do not cease to give thanks for you, remembering you in my prayers, that the God of our Lord Jesus Christ, the Father of glory, may give you a spirit of wisdom and of revelation in the knowledge of him, having the eyes of your hearts enlightened, that you may know what is the hope to which he has called you, what are the riches of his glorious inheritance in the saints, and what is the immeasurable greatness of his power in us who believe, according to the working of his great might which he accomplished in Christ when he raised him from the dead and made him sit at his right hand in the heavenly places, far above all rule and authority and power and dominion, and above every name that is named, not only in this age but also in that which is to come; and he has put all things under his feet and has made him the head over all things for the church, which is his body, the fulness of him who fills all in all.
For the husband is the head of the wife, even as Christ is the head of the church: and he is the Savior of the body.
He is the head of the body, the church; he is the beginning, the first-born from the dead, that in everything he might be pre-eminent.
1 CORINTHIANS 12:12-27
For as the body is one, and hath many members, and all the members of that one body, being many, are one body: so also is Christ. For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit. For the body is not one member, but many. If the foot shall say, Because I am not the hand, I am not of the body; is it therefore not of the body? And if the ear shall say, Because I am not the eye, I am not of the body; is it therefore not of the body? If the whole body were an eye, where were the hearing? If the whole were hearing, where were the smelling? But now hath God set the members every one of them in the body, as it hath pleased him. And if they were all one member, where were the body? But now are they many members, yet but one body. And the eye cannot say unto the hand, I have no need of thee: nor again the head to the feet, I have no need of you. Nay, much more those members of the body, which seem to be more feeble, are necessary: And those members of the body, which we think to be less honourable, upon these we bestow more abundant honour; and our uncomely parts have more abundant comeliness. For our comely [parts] have no need: but God hath tempered the body together, having given more abundant honour to that part which lacked: That there should be no schism in the body; but that the members should have the same care one for another. And whether one member suffer, all the members suffer with it; or one member be honoured, all the members rejoice with it. Now ye are the body of Christ, and members in particular.
2 CORINTHIANS 4:13-14
We having the same spirit of faith, according as it is written, I believed, and therefore have I spoken; we also believe, and therefore speak; knowing that he which raised up the Lord Jesus shall raise up us also by Jesus, and shall present us with you.
Fulfil ye my joy, that ye be likeminded, having the same love, being of one accord, of one mind.
"Sanctify them through thy truth: thy word is truth. As thou hast sent me into the world, even so have I also sent them into the world. And for their sakes I sanctify myself, that they also might be sanctified through the truth. Neither pray I for these alone, but for them also which shall believe on me through their word; that they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me. And the glory which thou gavest me I have given them; that they may be one, even as we are one: I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me."
DENOMINATIONS ARE CHANGES MADE BY MEN 1 CORINTHIANS 2:1-5
And I, brethren, when I came to you, came not with excellency of speech or of wisdom, declaring unto you the testimony of God. For I determined not to know any thing among you, save Jesus Christ, and him crucified. And I was with you in weakness, and in fear, and in much trembling. And my speech and my preaching was not with enticing words of man's wisdom, but in demonstration of the Spirit and of power: That your faith should not stand in the wisdom of men, but in the power of God.
1 CORINTHIANS 1:10-16
Now I beseech you, brethren, by the name of our Lord Jesus Christ, that ye all speak the same thing, and that there be no divisions among you; but that ye be perfectly joined together in the same mind and in the same judgment. For it hath been declared unto me of you, my brethren, by them which are of the house of Chloe, that there are contentions among you. Now this I say, that every one of you saith, I am of Paul; and I of Apollos; and I of Cephas; and I of Christ. Is Christ divided? was Paul crucified for you? or were ye baptized in the name of Paul? I thank God that I baptized none of you, but Crispus and Gaius; Lest any should say that I had baptized in mine own name. And I baptized also the household of Stephanas: besides, I know not whether I baptized any other.
[It would have been a sin for them to belong to the Church of Paul or Paul's Church, or call themselves Paulians. It is just as sinful to belong to the Lutheran Church (for Martin Luther), Baptist Church, or any church other than the one church that Christ made.]
Salute one another with an holy kiss. The churches of Christ salute you.
[The churches in different cities were each a church of Christ.]
I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel: Which is not another; but there be some that trouble you, and would pervert the gospel of Christ. But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed. As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed. For do I now persuade men, or God? or do I seek to please men? For if I yet pleased men, I should not be the servant of Christ. But I certify you, brethren, that the gospel which was preached of me is not after man. For I neither received it of man, neither was I taught it, but by the revelation of Jesus Christ.
1 CORINTHIANS 3:3
For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, are ye not carnal, and walk as men?
As ye have therefore received Christ Jesus the Lord, so walk ye in him: rooted and built up in him, and stablished in the faith, as ye have been taught, abounding therein with thanksgiving. Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ. For in him dwelleth all the fulness of the Godhead bodily. And ye are complete in him, which is the head of all principality and power:
"Ye hypocrites, well did Esaias prophesy of you, saying, This people draweth nigh unto me with their mouth, and honoureth me with their lips; but their heart is far from me. But in vain they do worship me, teaching for doctrines the commandments of men."
FALSE TEACHERS 2 CORINTHIANS 11:13-15
For such are false apostles, deceitful workers, transforming themselves into the apostles of Christ. And no marvel; for Satan himself is transformed into an angel of light. Therefore it is no great thing if his ministers also be transformed as the ministers of righteousness; whose end shall be according to their works.
Take heed therefore unto yourselves, and to all the flock, over the which the Holy Ghost hath made you overseers, to feed the church of God, which he hath purchased with his own blood. For I know this, that after my departing shall grievous wolves enter in among you, not sparing the flock. Also of your own selves shall men arise, speaking perverse things, to draw away disciples after them.
2 TIMOTHY 4:1-4
I charge thee therefore before God, and the Lord Jesus Christ, who shall judge the quick and the dead at his appearing and his kingdom; preach the word; be instant in season, out of season; reprove, rebuke, exhort with all longsuffering and doctrine. For the time will come when they will not endure sound doctrine; but after their own lusts shall they heap to themselves teachers, having itching ears; and they shall turn away their ears from the truth, and shall be turned unto fables.
IF IT ISN'T CHRIST'S CHURCH, IT IS THE DEVIL'S CHURCH 1 CORINTHIANS 10:21
Ye cannot drink the cup of the Lord, and the cup of devils: ye cannot be partakers of the Lord's table, and of the table of devils.
1 CORINTHIANS 14:33
For God is not the author of confusion, but of peace, as in all churches of the saints.
2 JOHN 1:9-11
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. If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed: for he that biddeth him God speed is partaker of his evil deeds.
1 TIMOTHY 4:1-5
Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils; speaking lies in hypocrisy; having their conscience seared with a hot iron; forbidding to marry, and commanding to abstain from meats, which God hath created to be received with thanksgiving of them which believe and know the truth. For every creature of God is good, and nothing to be refused, if it be received with thanksgiving: for it is sanctified by the word of God and prayer.
"Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven. Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? And then will I profess unto them, I never knew you: depart from me, ye that work iniquity."
ANY OTHER THAN THE LORD'S CHURCH OFFERS THE SAME RESULT JOHN 15:6
"If a man abide not in me, he is cast forth as a branch, and is withered; and men gather them, and cast them into the fire, and they are burned. If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you."