Why are there so many denominations of Christians.?

The word Denomination answers your question partially. It means something that is named. Humans name them, and they are distinguished by human doctrines.

The prophecy given by the apostle Paul sheds some additional light on the subject:

Acts 20:29-30

I know that after my going away oppressive wolves will enter in among you and will not treat the flock with tenderness, 30 and from among you yourselves men will rise and speak twisted things to draw away the disciples after themselves.

This is what happened to Christianity. People who wanted to be the authority about how to please God, and everybody else had to obey them.

Or, people who wanted all of the benefits of being a Christian, but did not want to be obedient.

Titus 1:16

They publicly declare that they know God, but they disown him by their works, because they are detestable and disobedient and not approved for good work of any sort.

The Israelites were given the sacred pronouncements of God. But Jesus himself, the Son of God, spoke of a similar situation among his countrymen on earth - quoting Isaiah, who referred to Jesus' God and Father:

Matthew 15:8, 9

‘This people honor me with their lips, but their hearts are far removed from me. 9 It is in vain that they keep worshipping me, for they teach commands of men as doctrines.’

However, even today, there are some who will worship the Father in spirit and truth, and who will show themselves to be disciples of Christ by their active faith and their love for one another.

So the thought isn't the many numbers of denominations of nominal Christians, but about each one of us must be searching for God through Jesus Christ, our Lord, Savior and Ransomer, and doing this, humbly and obediently, every day. As he said:

"By this all will know that you are my disciples, if you have love among yourselves."

https://www.jw.org/en/bible-teachings/questions/ar...

https://www.jw.org/en/publications/magazines/wp201...

The Bible states there is only one True religion.

Eph 4:5 one Lord, one faith, one baptism;  one God and Father of all, who is over all and through all and in all.

If you could ask Satan your question, he would be most happy to answer your question, because all other religions belong to him.

Religious leaders are to blame for that. They have caused much of the confusion. They do not teach what the Scriptures really teach. They have “twisted” Bible teachings.

Good question, and it would take a lifetime to look into each one of the 1,000s of denominations, however....

Please look at True Christianity:

THOSE WHO WORSHIP THE TRUE GOD

People of many races, ages, and circumstances following the way of true worship

base their teachings on the Bible

worship only Jehovah as the God of Abraham and make his name known

show genuine love for one another

accept Jesus as God’s means of salvation

are no part of the world

will NOT take up arms against ones fellow man

preach God’s Kingdom as man’s only hope

See

How can we identify the true religion?

https://www.jw.org/en/publications/books/bible-tea...

Each denomination in the Christian church identifies a minor split from the teachings of the Bible. As unfortunate as that is, it's a common problem among all religions. Islam has 57 individual sects, Buddhism, Hinduism, Sikh, Shintoism, Judaism, and even paganism all have multiple versions of themselves. They are created according to individual preferences concerning "how" to worship and follow each set of teachings.

that is all the result of man's ego, pride, and greed........ and the mine-in-bigger-than-your's syndrome.... none of the man-invented "denominations", claiming the title of Christian, have any authority, from The Creator God, for their existence

There is only One True Church commissioned by The Creator God... and only God decrees who becomes a part of The Body of His Church... and only those of The True Church will enter Heaven

Many people wants to feel like they are good Christians. 2 Timothy 4:1 I solemnly charge you before God and Christ Jesus, who is to judge the living and the dead, and by his manifestation and his Kingdom: 2 Preach the word; be at it urgently in favorable times and difficult times; reprove, reprimand, exhort, with all patience and art of teaching. 3 For there will be a period of time when they will not put up with the wholesome teaching, but according to their own desires, they will surround themselves with teachers to have their ears tickled. 4 They will turn away from listening to the truth and give attention to false stories. 5 You, though, keep your senses in all things, endure hardship, do the work of an evangelizer, fully accomplish your ministry.

There isn't--Jesus began one single religion--the other 99% claiming to be Christian aren't. 1Cor 1:10--Mark 3:24-26

The world is very confused on this matter.

The religion that came out of Rome is this-2Thess 2:3 and all of its 33,000 branches.

There is no god so people guess. Different people make different guesses.

Well, it is not as though there is any objective way of determining which beliefs are right. Not unless you count the complete failure of Jesus' prayer that all his followers should be as one so that the world can know that he was sent by God, which would indicate that all Christian denominations are wrong.