Division was condemned, and denominations did not exist in the time of the apostles.The first clause of that statement is correct. For example, in 1 Corinthians 1:10, the apostle Paul wrote:
Now I urge you, brothers, in the name of our Lord Jesus Christ, that you all say the same thing, that there be no divisions among you, and that you be united with the same understanding and the same conviction.But the second clause is incorrect.
As you may recall from previous posts, such as this one, and this one, the church was originally completely Jewish, and those Jews still kept the Mosaic Law. You can see this pretty clearly in Acts 15:5 which says:
But some of the believers from the party of the Pharisees stood up and said, "It is necessary to circumcise them and to command them to keep the law of Moses!"Likewise Acts 21:20ff which says:
When they heard it, they glorified God and said, "You see, brother [Paul], how many thousands of Jews there are who have believed, and they are all zealous for the law. But they have been told about you that you teach all the Jews who are among the Gentiles to abandon Moses, by telling them not to circumcise their children or to walk in our customs. So what is to be done? They will certainly hear that you've come. Therefore do what we tell you: We have four men who have obligated themselves with a vow. Take these men, purify yourself along with them, and pay for them to get their heads shaved. Then everyone will know that what they were told about you amounts to nothing, but that you yourself are also careful about observing the law.Notice that we have Jewish Christians who are "zealous for the law" and are upset that Paul might be teaching the Jews living outside Judea that they don't have to follow the law, but that they're mistaken: Paul is not teaching this, and in fact, Paul himself keeps the law. It's hard for us to accept this, believing that keeping the Law is inconsistent with being a Christian, but there it is in the inspired black-and-white of the text.
Then the next day, Paul [followed their advice].
Notice also that these Law-keeping Jews don't object to the Gentile believers not keeping the Law, but they are adamant that the Jewish believers should continue keeping the Law. (Later on, Paul makes it clear that keeping the Law is a non-issue; what's important is that one does not seek to be justified by keeping the Law.)
So the inspired record makes it clear that there were two "denominations" of Christianity in the first century during the lifetimes of the apostles: a Jewish, Law-keeping "denomination", and a Gentile, non-Law-keeping "denomination".
Call them "splinter-groups", "sects", "branches" or whatever other term you wish to use, but the fact remains, there were at least two denominations in the first-century church.
That does not justify the modern-day multiplicity of denominations we see in our world; as mentioned, the New Testament does indeed condemn division.
However, if we interpret Paul's condemnation of division to mean that there should be no differences in our outward forms, then Paul was condemning himself and the leaders of the church in Jerusalem and the compromise made by the Jerusalem church as recorded in Acts 15. Perhaps instead we should interpret Paul's condemnation of division to mean that we should learn to get along with each other even if some of our outward forms differ, like the Jewish and Gentile Christians got along even though one group kept the Torah and the other did not.
Of course the question is then raised, "Where do we draw the line?"
The historical answer since the early days of the Restoration Movement has been, "In essentials unity, in opinions liberty, and in all things love."
Now if we could just agree on what are "the essentials" and what are "the opinions". But that's a whole 'nuther issue.