They all claim that they worship the Creator God and that there is one Creator God but they ascribe different characteristics to this God. Even different names. The Islamic faith is like Mormonism for the seventh century, while Joseph Smith wanted to make a religion based around a biblical topic based on phoney texts that made the Americans the chosen people, Mohammed did that for the Arabs. While Smith was not much of a one for leading people into battle he did make a lot of parallels with Mohammed, including the multiple wives thing. In the case of Mormonism you have texts which are supposed to have been written in a language called Reformed Egyptian, although nobody can see this language and Joseph Smith is supposed to have had something called the Urim and Thummim (a Biblical idea but we’re not sure what they are) to interpret this text, and the original is in golden plates given by the angel Moroni which nobody else was allowed to look at. They ask anyone willing to talk to them to pray and ask God whether these things are true, but when I did so the answer that came to my head was that whenever before God has spoken, he has protected the language of these revelations so that Hebrew, Aramaic and Koine Greek are still spoken or understood at least almost natively today in the face of overwhelming enemies and opposition. Even the Qur’an was in a language kept until today but in their case, they were the overwhelming proposition, so to speak, so I am not counting that.
Muslims
The Muslims claimed that Moses and others were all good Muslims but others had twisted their words and only the Qur’an (plus the Hadith and Sunna, as in fact you don’t get most of the doctrines in practice from the Quran alone) is a copy of the Umm al Kutub or Mother of all Books (if I got that bit of Arabic wrong excuse my memory) and is a copy of the Book which is with Allah in heaven. On the one hand they say that these texts are a revelation for the Arabs and have to be kept in Arabic, but on the other if taken all together you see they contain an expansionist statecraft which adds up to a political exceptionalism for Muslims, and especially for Arab Muslims. Unlike the Bible or other texts for that matter, the holy texts make demands on Muslims which basically prove it was intended initially only for one time and place. The Feast of Ramadan can’t be kept in the polar regions as you would never get to your iftar for half the times Ramadan is kept. The Hajj can only be kept physically by a tiny proportion of Muslims if you look at the logistics, whereas the religion says every Muslim is supposed to do it at least once in their lives. I will leave you to to your own maths and if you can see a way to actually enable this to happen, by all means use the comment section. I don’t censor for disagreement as long as it is civilised and not spammy or vulgar or satanic.
Jews
Jews have developed their views in a rather complex way, adding layers of complexity with each additional text so that in essence you have a Talmud sitting there much much bigger than the Old Testament and taking certain ideas from Torah and Tanakh in very different directions than the New Testament takes them, but still they seem rather a lot closer to Christianity than Islam in that they do at least have three quarters of the same Bible as we do, pages wise, anyway. And there are many flavours of Judaism so that in a sense talking generally about Judaism is nearly as prone to be misleading as talking in generic terms about Christianity. There are Jews on both sides of very big fences both in politics and in ethics, as well as in questions of our origins in Creation and our destiny in the afterlife. There’s nothing new in this really – Pharisees and Sadducees as well as other sects of Judaism where in deep disagreement about some of the most fundamental questions even at the time of the New Testament, as can be seen from the life of Jesus as well as the Acts of the Apostles and some of Paul’s letters, among others.
Christians differ from most Jews over the person of Jesus Christ and the authority of the New Testament. We believe in the Trinitarian formula which makes Jesus absolutely unique and the Bridge between God and Man. Son of God and Son of Man are titles used of Him almost interchangeably. John 17 shows an amazing secret about who Jesus is and who He is also before He was born of Mary. Jews have not accepted this in the main however there have always been some who have indeed accepted this and come to know Jesus in a Christian way. There are then two opinions on whether they are still Jews if they do. Many will say that they are not, but others will say they are except only in the sense that Talmudic Judaism has gone its own way and defines Judaism around itself, whereas in fact there are many ways of being a Jew, and always have been, at least for a couple of thousand years at any rate.
Roman Catholics
Roman Catholicism is one of the Christian churches, but has the problem that it holds particularly closely to ecclesiastical traditions and structures and derives as much authority from them as from the apostolic writings to the extent that they consider themselves to be in a straight line from the apostles and that the protestants have gone off at a tangent. The fact that they still have larger numbers than the rest seems to confirm them in this view, despite Jesus’ warning that it isn’t about numbers. Protestants however see themselves as having abandoned a lot of medieval entropy and gone back to the very text of the New Testament. Along with this, we focus back on the central role of Jesus in saving us and applying this salvation to us via faith. Apostolic succession seems to Protestants to be a self-serving doctrine wrung from a handful of verses by those who would be served by thinking thus. And in practice, when we consider via what kinds of people this line of succession has gone and how many of them put carnal, earthly considerations before those of God’s kingdom, the doctrine seems to ring very hollow indeed.
Roman Catholicism uses certain terms in quite different ways to the way Protestants use them, for example they use the term “sacraments” to cover quite a lot of things while for us there are only two: baptism and the lord’s supper. They say that the lord’s supper, which they call the Eucharist, is a “means of grace”, a term also used by Protestants but with the meaning of praying and reading the Bible. They think that the bread and wine turn literally into the body and blood of Jesus but as a Passover meal, but what these things do is show that Christ is the Passover, it was because of Him being that Lamb that would take away the sin of the world that in the first Passover the blood on the lintel and the lamb eaten by all who were to be saved turned away the avenging angel and got them through the Red Sea which fell on their pursuing enemies. The Passover Lambs did not need to turn into the blood and body of the the future Messiah for this purpose but it got them through the Red Sea.
Protestants
And then within Protestantism also we have various disagreements as to who should be baptised, how often the Lord’s supper should be taken, predestination versus a total volitional approach, as if these were contradictory, which in fact they are not (unless you have the mind of a child who also cannot understand how Quantum mechanics can be true and Newton’s or Einstein’s physics also true) and questions of Church governance, end-times prophesies and worship styles.
Same name, different God
So in a sense we have the same God but at the point at which we ascribe to God varying characteristics and varying expectations from us, in a sense we have a different God. Just as Paul warned the Galatians against accepting “another Jesus”. He didn’t mean a different person coming along claiming to be Jesus (the NT warns about that also, in other places, but this isn’t what Paul has in mind when talking to the Galatians) but another view of what Jesus did and what it meant, and how to apply it for our salvation. It was tantamount to having another Jesus and thereby, another God.