Denominations exist everywhere, but I wanted to focus on ones in Christianity. Generally when you argue with someone in a denomination typically they'll operate on the denomination's principles (as ridiculous or correct they may be). I wanted to plot as to WHY denominations are wrong.
#1 Denominations are not found in the Bible. Christ does not specify one that is the truth, it's just not there. Sure you have Israel and different dispensations (re: Israel rejecting Messiah, passed on to gentiles)-- but that's still not explicitly a denomination in the sense what we're dealing with. And even if it was, then that would eradicate all of the weird Christian denominations today. FURTHERMORE, denominations have cropped up AFTER Christ and AFTER the Bible was written.
#2 Denominations often add EXTERNAL material to circumvent the Bible. Catholics and Orthodox add the apocrpyha (with different flavours as they don't all agree which is canon), and the Catholics also add the catechism. Mormonism adds the Book of Mormon along with Pearl of Great Price. Judaism adds the talmud (although not a Christian group, but still modifies the Word). Jehovah's Witnesses have to use a special translation (NWT), which makes some serious debatable changes. These are some of the more common ones. We really have to ask the question WHY they are adding material that can easily be proven to contradict the Bible (the Word).
#3 Denominations blatantly CONTRADICT the Bible, and then attempt a weak excuse to cover it. In some cases they're forced to accept bizarre interpretations of the Bible where it visibly comes out (re: Christ saying "I AM" for unitarians, re: Christ saying "I am THE Rock" for Catholics, re: Christ saying 'only believe' for Jehovah's Witnesses). This phenomenon can be explored with 'contradiction parallelism', in which all denominations behave in the same way to bypass contradictions causing a huge mess when you add them all up and view them in unison (makes them all look stupid). I will explore this in another thread because it really shows that *all* denominations are wrong.
#4 Denominations foster a superiority complex that feeds itself. So, person X in denomination Y is correct because their denomination has "history" or "councils". So the 'proof' for the denomination is itself, which isn't a proof... just like macro evolution! Which may just be a characteristic of religion in general.
#5 Denominations are not necessary and useless. This is a big one: GOD DOES NOT *NEED* your help. He doesn't even need help from any group. And none of the groups we're faced with in Christianity exist in the Bible. So if denominations don't serve a purpose--is there an ulterior motive? Yes, because they specifically try to bypass the Bible, deliberate misguide their followers and reverse things that are obvious and/or shouldn't be reversed. In which case we get into the whole satanic reversal thing-- satan SPONSORS denominations.
#6 Denominations restrict the Bible being 'open', not all exhibit this-- but a handful do. Catholics are probably the most historically known: but now we have Jehovah's Witnesses who slink away in their NWT and refuse it to be distributed by any 3rd parties. Or the KJV-only movement which restricts what Bibles you can read and eliminates the original language texts just like the council of trent. I mean what kind of Christianity is that, which LIMITS and BUTCHERS the Bible? Christ's very words? That shows the denomination is not interested in God's Word and would rather spew nonsense.
#7 Denominations crop up in RESPONSE to issues satan does not like. This one is a bit more experimental (and you're going to find less people that agree with it). In many instances the spawning of denominations are a 'response' from satan when something happens in Christendom that isn't good for his cause. Like finding fantastic ancient manuscripts, doctrines that have been in PLAIN VIEW but everyone ignores and are being pointed out again, many people getting interested in the Word in a cluster. And if you think about it, all of this is regarding THE BIBLE (not any of the extra garbage denominations put in) and the individual interested in the Word.
So... with all of that combined, it starts to become OBVIOUS that *no* denomination is correct. The whole PURPOSE of a denomination is actually against the Bible: in that you as a believer have a personal relationship with Jesus Christ. It's between YOU and GOD. Denominations add extra overhead that starts to breakdown Bible Doctrine--at some point or another. Because the focus is no longer on YOU and GOD, it's YOU and YOUR DENOMINATION (and then God is put on the sidelines).
Disclaimer: denominations are here to stay, and saying this won't change anything. God even sometimes uses faculties of denominations for His Purpose and some believers may require them (but what's that saying, as God used a wild ass to speak, so denominations may as well just be classified as ass). You may need to be in a denomination at some point, but as you grow in Bible Doctrine, I think everyone will have to outgrow it at some point. Taking it further, some people may like the aspects of a denomination and ignore the "Bible" aspects. Well then there you go, denominations are good for everything but Bible Doctrine and supports the theory that when you grow, you outgrow them INEVITABLY. If you don't grow, you remain in that stage.