In discussing Islam on another website, the argument was made that because Islam does not regard Jesus as God, and because the Bible clearly DOES teach that Jesus is God, Islam rejects the Bible. A variation of the same sort of argument is often used against various groups claiming to be Christians. Since they don't believe orthodox teaching, and since the Bible “clearly teaches” orthodoxy, then these groups are not Christians.
While I have no intention of defending everything that Islam or every heterodox Christian group believes in, the argument above is presumptuous and unhistorical.
Even using the books of the Bible that we have come to regard as canonical (our current New Testament for example) there was a tremendous battle over such questions as the divinity of Jesus. For a number of years, Arianism (which taught that Jesus was a divine, but CREATED being – inferior to the Father) was the dominant viewpoint in Christianity – and they had plenty of verses in our current New Testament to back them up. Jehovah's Witnesses believe much the same thing today.
But what we also need to realize is that our current New Testament was specifically selected by the proto-orthodox Christians. The Gospels we have (Matthew, Mark, Luke and John) were not the only Gospels circulating in the early Church. The epistles and apocrypha we have in our current Bible are not the only ones that could have been selected. The ones that were selected were chosen PRIMARILY because they taught the orthodox viewpoint.
There were many groups of Christians in the early Church. The range of their beliefs was even more diverse that our modern versions of Christianity. Each group had it's own collection of writings – of Gospels and epistles and apocryphas – that supported its own point of view.
One of the earliest groups in Jerusalem were the Ebionites. Their beliefs were in many ways similar to Islam. They believed Jesus was a great prophet – but only a human being. He had come to revitalize Judaism and set it on the right path.
Then there were the Marcionites, to whom Jesus was not human at ALL. He was entirely God, and his humanity was simply a facade. To the Marcionites, Judiasm was a false religion created by a false god from whom Jesus had come to set us free.
All of these groups, as well as the proto-orthodox, who staked out a middle ground on the nature of Jesus, had scriptures to support their theology. But once the proto-orthodox position became the dominant one in Rome, Rome used its political influence to not only exclude other points of view – but to create a list of scriptures that ALSO excluded other points of view. Scriptures that didn't fit the proto-orthodox theology were destroyed or hidden. In spite of this, there were enough remnants of divergent points of view left in the canonical scriptures to keep the orthodox arguing about the nature of Jesus for centuries
An excellent book on this by one of my favorite scripture scholars (Bart Ehrman) is:
Lost Christianities: The Battles for Scripture and the Faiths We Never Knew
The point of the proceeding is that it is circular to claim that the Bible obviously proves orthodoxy when the Bible was specifically selected and edited to prove orthodoxy. Even with the aggressive selecting and editing (and even forging) there is enough variety in the Bible to have kept Christians arguing for centuries. The nature of Jesus is not “obvious” from the Bible, and Islam, for all it's peculiarities is not “obviously” trying to be anti-biblical (much less anti-Jesus) by questioning orthodox dogma.