Division does not please God at all. That's what denominations basically are, divisions. And they name themselves after persons, things, doctrines, or places, other than Christ.
They are not in the perfect will of God, never were, never have been, never will be.
Once the church was all believers in a city. There are no letters written to denominations in the bible, but only to all believers within a particular city.These believers separated into parties, sects, according to the person or doctrine they followed (1 Cor 3:4). Over time they organized themselves and become organized divisions, or denominations.
There's no reason why 30 believers on one street cannot worship with the other 50 believers on the same street, if they all have the same Holy Spirit, one life, one Father, one Lord, etc etc.
Denomination not only upsets God, it sends the wrong message to the world and damages Christ's testimony of one body on the Earth,, and as much as denominations talk about loving one another, they are not practicing it, if they don't meet and fellowship together. It's like saying I love my family but never spending time with them.
Jesus prayed for unity in John 17. So denominations are not satisfying this prayer.
But on the other hand He expected division, knew it would happen, and uses it to accomplish His purpose. This is His permissive will. This does not mean God does not use denominations. But I would question whether God really does instruct some people to start a new division when they are not happy with the division they are already in.
But unity brings blessing:
Ps 133:1 A song of ascents. Of David. How good and pleasant it is when God's people live together in unity!
The bible defines churches as the church in Jerusalem, church in Antioch, church in Rome, church in Ephesus etc etc. From God's point of view, a church is every believer in a particular city. But this church is still one church with all the other churches on the Earth. That is, it is not church of Jerusalem, but church in Jerusalem. It is the church of God in Jerusalem.
This is where Roman Catholicism falls short, even though it believes in one worldwide church and unity, which is kind of good - there is no such thing as a "church of one place" existing in another place. The "church of Rome" in another city makes no sense according to the bible. Catholicism is basically another denomination and imposes the practice of Rome on other cities. When in the Bible, each church in each city was allowed to form and shape itself according to its own culture, language etc, and overseen by elders within the church itself, not from afar by a pope or bishop.
There was no such thing as churches named after nationality, country, race, doctrine, practice (eg baptism). And there was no such thing as a "non-denominational" church, which in itself is a denomination.
Isn't it funny how because of denominations, the true church feels it has to define itself as "non-denominational"?
It's like a Christian church having to define itself as "non-Hindu", or "non-Buddhist".
Basically according to the bible, church is about assembling ourselves together with all the believers in the city in which we live for fellowship in the Holy Spirit and with each other.
It says assemble yourselves together (Heb 10:25), not organize yourselves together. Denominations are basically groups of Christians who organize themselves together for a specific purpose other than fellowship of the Holy Spirit. Usually this organizational purpose is to conduct services centred around a particular style or flavor of worship. The concept of a "service" itself is for a few specially gifted people (pastors, priests) to minister something spiritual to the majority congregation who normally just receive and do not participate or use their spiritual gifts in the service.
This concept of a service itself is foreign to the bible since all believers were encouraged to participate and use their spiritual gifts
1 Cor 14:26 "When you assemble, each one has a psalm, has a teaching, has a revelation, has a tongue, has an interpretation. "
It does not say " when you assemble, only the pastor or priest or theologically trained people has a teaching, revelation ", which is the practice of almost all denominations today.
Actually the bible doesn't say we can separate or organize ourselves to worship together in different styles, it only says we must worship in spirit and truth (John 4:6-30) and let there be no divisions among you (1 Cor 1:10).
We can note that when Paul said let there be no divisions among you (1 Cor 1:10), He was writing to the church in Corinth.. that is, all the believers in the city of Corinth. He was not writing to a denomination or a small group within the city.
But denominations have reinterpreted this verse to mean that "if there is no division in our denomination, then everything is OK". Wrong - Paul meant for all believers in the whole city to not be in division. This rules out the existence of denominations altogether.
Behind denomination is basically some of these things:
Independence and spiritual pride: a denomination is basically a limb of the body that says "I don't need you" to the other parts of the Body (1 Cor 12:21)
spiritual pride: believing one way of practice is better than another which causes them to avoid fellowship with others, when the bible says we are all brethren and equals.
personal preference: this is basically selfishness, the belief that I should be able to worship in the way I want to, so I will find or even start a group that worships the way I like. This will cater to every kind of taste in music, hymns, fast songs, slow songs, grape juice, wine, the right kind of bread.
Idolatary: denominations have created their own "golden calf" for themself, whether it is spiritual gifts, the ceremony of bread and wine ( the mass, communion etc), method of baptism or worship style or insistence in speaking in tongues in corporate way. These things have become #1 priority over fellowshipping in the Spirit with all believers, because it is upon these types of things that they separate and divide themselves. I know of a decades long rift between two particular protestant denominations over dispute regarding the bread and wine.
Division begets division and this is why divisions continue to occur again and again. The reason division occurs is because people are not willing to bear the cross. The solution to division is humility, considering others better than ourselves, and love and acceptance, and most of all, discerning the Body of the Lord.