It is a fact of history that almost all denominations came into existence many centuries after the time of Jesus Christ. Denominations were unknown during the times that the apostles of Christ lived and wrote the New Testament. Divisions, or denominational tendencies, that is, the tendency for one group of Christians to teach a doctrine different from that taught by another, were known about and experienced during the first century. Contrary to many religionists today who praise division or denominationalism, the apostles (by the guidance of the Holy Spirit of God) who wrote the New Testament condemned denominationalism. Paul, in 1 Corinthians 3:3-4, corrected the congregation in Corinth by saying;
"…for you are still carnal. For where there are envy, strife, and divisions among you, are you not carnal and behaving like mere men? For when one says, “I am of Paul,” and another, “I am of Apollos,” are you not carnal?”
In 1 Corinthians 1:10, Paul also discussed division, or denominationalism;
"Now I plead with you, brethren, by the name of our Lord Jesus Christ, that you all speak the same thing, and that there be no divisions among you, but that you be perfectly joined together in the same mind and in the same judgment." (Study also Romans 16:17).
Thus, we can see that there were no denominations in the original New Testament church, indeed, the few small schisms as came into existence were quickly extinguished by the apostles. Denominationalism was neither necessary nor desirable. Then, we must ask, to what church did the Christians of the first century belong? It had to have been the Lord's church or body of Christ that Jesus died to save, that only and no other - Acts 20:28.
It is both reasonable and logical to ask, "Can I join the Lord's church today?" If one could join the Lord's church today, he would not be joining a denomination. The Lord's church is not a denomination nor does it contain denominations. The Lord's church would have all its New Testament markings and would not have those markings identifiable with denominationalism.
The main identifying mark of the Lord's church is that of a strict compliance with and submission to the apostle's doctrine as revealed in the New Testament. Creeds or other books (in addition to the Bible) and additional revelations are not needed and are against the teachings of the apostles who wrote in Galatians 1:8-9, " But even if we, or an angel from heaven, preach any other gospel to you than what we have preached to you, let him be accursed…" The Bible reveals that all the knowledge that is needed for us to do every good work has already been supplied. Read 2 Timothy 3:17 and 2 Peter 1:3 . Additionally, 1 Corinthians 4:6 warns us against going beyond that which has been written.
Other things that identify the Lord's church are, having Christ as its head rather than some earthly person or office; having its headquarters in heaven rather than in some earthly city: and its members use the name Christian rather than some denominational name. Study Col. 1:18, 3:1, and 3:17.
But, how do men, today enter this pre-denominational church? Simply by doing the same thing that was expected of people in the first century: For the words of the apostles are to all mankind of any race and any century. They are for us.
One first and obvious step is believing that Jesus is the Christ and that through Him, and Him only, mankind can be saved.
But, contrary to the teachings of man, we must continue beyond this simple belief or acknowledgment. We must be obedient to the commandments of Christ, for Jesus said, "If' you love me, keep my commandments" (John 14:15). Obviously we must believe fervently that Jesus is God's Son, our Savior, The Christ. We must be obedient to both the commands of Jesus and those of the apostles. The apostles were told what to write in the Holy Scriptures which are the New Testament, for Jesus promised, "But the Helper, the Holy Spirit, whom the Father will send in My name, He will teach you all things, and bring to your remembrance all things that I said to you" (John 14:26).
There are several things a believer must do before he becomes a member of the Lord's church. One of these is to believe, another is to repent (to turn away from a sinful life - Acts 17:30) and yet another is to be baptized into Christ for the remission of sins. Few teach baptism for the remission of sins and this requirement is yet another marking of the Lord's church, for Acts 2:38-47 reads, in part;
"Then Peter said unto them, “Repent and let every one of you be baptized in the name of Jesus Christ for the remission of sins . . . Then those who gladly received his word were baptized; and that same day about three thousand souls were added to them . . . And the Lord added to the church daily those who were being saved".
Thus, you cannot join the Lord's church in the sense that you join a club or other man-made organization. Through your complete obedience to the will of God you demonstrate your total trust in Him. God will then add you to the Lord's church, to this only, and none other. Thus, in this ancient manner it is possible to become a Christian without joining any denomination.
Adapted from an article in The Interactive Bible (http://www.bible.ca/r-non-denominational.htm), and Bible quotes are from the New King James Version.