Pre-Islamic Arabia had a fair few religions present among its population. There was traditional Arabian polytheism, Christianity of various types (primarily Nestorian), Judaism and Zoroastrianism, to name most of them. That changed when Islam and the Rashidun Caliphate rose.
I have a pretty baseline understanding of the Islamic religion. However, looking at Islam, I can see a ton of influence from the religions that preceded it. Muhammad himself was influenced by Nestorianism IIRC, and Islam considers Zoroastrians, Jews and Christians people of the book, and is more tolerant of them than of pagans. The principle of Tawhid in the Shahada is very Abrahamic.
Islam is still, however, a religion that is Arabic to its core, and reflects the Arabian cultural and social environment it was created in, despite having a solidly Abrahamic theology. It's like a uniquely Arabic reaction to Abrahamic religion.
So I was thinking- why can't this happen in Europe around the time of Christianisation? A uniquely-European Abrahamic religion, with a new prophet and principles reflecting both its Abrahamic theology and European roots.
Is it even historically possible for there to be a Muhammad analogue born not in the Arabian desert, but in the forests of Scandinavia or at the foothills of the Carpathians? For the influence of Christian missionaries among the Slavs or the Norse or the Balts to go horribly wrong and spawn an entirely new religion? I'm thinking this would happen quite early, probably around when Islam became a thing.
Our hypothetical prophet doesn't even have to be that successful- what I am interested in is what a European-grown Abrahamic religion would look like.
What doctrines and principles would it likely hold? How would it synthesise traditionally Christian/Jewish ideas with local European ideas? How would the situation in Europe at the time make it differ from Islam in its implementation? (Christianisation was motivated in part because it benefited nobility, for instance)
What would, say, a Slavic or Germanic-derived Abrahamic religion even look like?