There is no universal Christianity. A uniform Islam does not exist.
Buddhism comes in many varieties. Hinduism varies a great deal in different regions.
It is a common error to consider those religions to have common beliefs and practices everywhere. It is a mistake to talk about Christianity in general. Like most major religions, it is made up of an almost endless set of sub-religions, each with its own view of what it is to be a Christian. Denominationalism and Schism is the order of the day in Christianity, as it is in most major religions.
In every city in the United States, one can attend Christian churches of many varieties. In my own metropolitan area, I could attend a different church every Sunday for many years without visiting any of them twice. Over here, there is a church that espouses racism as a fundamental belief. Over there is one that welcomes all people and accepts all variations. Just down the road is one that conducts its liturgy in Old Church Slavonic, a language spoken by nobody. Across town is a Traditionalist Catholic Church that has splintered off from Rome and uses Latin exclusively in its services. There are ELCA Lutheran churches, Missouri Synod Lutheran churches, and Wisconsin Synod Lutheran churches from which to choose, each with its own interpretation of Martin Luther's ideas.
In the Twin Cities, one can attend services conducted in Norwegian, Swedish, German, Vietnamese, French, Spanish and many other languages. There are even several Christian churches with liturgies in Hmong and Somali. One can read or study the Bible in dozens of translations into English alone. Each church decides which translation is really the "word of God."
All purport to be Christian churches. Yet, they have little in common with each other in terms of doctrine, dogma, and attitudes toward just about anything you could name.
There is no one Christianity. There are thousands of Christianities. Humans cannot, apparently, come together with any given set of beliefs and understandings.
It is a mistake to lump all Christians together. It is a serious mistake, one which can lead to utter confusion. The same is true of other faiths. I speak of Christianity because it is the dominant religion in my own country. Still, I know nothing about a person if the only thing I know is that the person calls him or herself a Christian. Nothing.
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I guess the exception that proves the rule. I could change my statement to all but one. 