Last year I obtained and read the book Early Arianism - A View of Salvation by Robert C. Gregg and Dennise E. Groh.
Before I read this book I thought of the Arian heresy as being like as a Tolkien Nerd viewing Jesus as Manwe rather then Eru Iluvatar, due to it being defined casually as believing Jesus isn't Co-Eternal with The Father but is still Divine in a sense including still having a Preexistence as The Logos.
However reading this book and how well it quotes what little we have of the arguments of the Earliest Arians (and responses to them) has made me realize that they did view Jesus as being in His core essence no different from any other Human, even how He's the Son of God is simply as the First-Born of how all Believers are Sons of God.
They did believe Jesus had a Pre-Existence, but if they believed all Humans also had a Pre-Existence then that doesn't conflict with what I just said. The book doesn't address that, but it does show they put a lot of emphasis on arguing Jesus did not have any inherent advantage over other Humans in His ability to be Sinless. If only He had a Pre-Existence then that would be an advantage.
I'd spent years being annoyed at Arianism being characterized by uninformed casuals as being a belief that Jesus wasn't Divine at all but just a Human. The truth is however that is exactly what the Early Arians believed, they only believed Jesus to be Divine in the same way they and Orthodox-Nicene-Trinitarian Christians ultimately believe all Humans to be Divine (or all Believers at least). They were different from other ways of denying the Deity of Christ only in the semantics of how they define things.
This book was about stressing the Arians' view of Salvation, but by that it means the how of Salvation, so for example whether or not the Arians even considered Universal Salvation doesn't come up. All the Proto-Pelegian stress they put on Free Will makes it seem unlikely at first glance, but Athanasius put some stress on Free Will as well and we know he taught Universal Salvation.
What the title of the book means by Early Arianism is the very first generation, Arius himself, Eusebius of Nicomedia and one or two other less well known contemporaries of them. The Arians who were prominent later in the 340s-80s were divided into three distinct sects who some might argue none of which was really a pure continuation of the original Arianism. So the possibility that one or two or all of them became the Manwe-Jesus type Arians I initially thought of is still possible, but I don't know everything about any of them.
Two of these groups get called Semi-Arians, the Homoiousians (who in time became almost entirely also Pneumatomachi/Macedonians) and the Acacians also called Homoians/Homoeans. These kinds of Arianism were the ones actually advocated/promoted by the two Arian Emperors and went on to become the Arianism of the East Germanic Barbarians. The third group were the Aetians also called Anoumians, Eunomians, and Heteroousians, and some modern scholars even call them Hyper-Arians.
On the issue of Ousias itself the Acacians were the ones following Arius's original intent, it was Constantine himself who added Homoousianism to the controversy at Nicaea, the Ousias of Christ wasn't part of Arius's original definition of his beliefs at all. However in other ways Acacius of Caesarea does seem like he was compromising. It may well be the "Hyper Arians" who were the true Arians of this period.
During the Reign of Constantius II Arianism gained a presence in Arabia via Theophilus the Indian. Theophilus however had a complicated relationship with the Arian Emperors since he ultimately sided with the Aetians. Aetius himself was Syrian and the boundary between Syria and Arabia was pretty flexible in Roman times, they never built any major walls there.
Mawiyya was a Pro-Nicene Arab Queen rebelling against the Arian Emperor Valens, but Valens was also persecuting the Aetians so maybe the Aetians among the Arabs weren't really hindered by Mawiyya at all?
I have prior posts on this Blog exploring the theory of Islam being originally a heretical sect of Christianity. I do believe Mohammad literally existed and that his hostility to the Fatherhood of God made his brand of Abrahamism from the start distinct from whatever older sects it descends from. I also still support the Petra as the original Mecca theory.
Now my past looking into this focused on the Ebionites and then Nestorians. However while doing that I did stumble upon how two of the earliest Christian discussions of the religion of the Arab Conquerors of the East defined them as being Arian in origin, Honorius who was Bishop of Rome at the time of the Arab Conquest and John of Damascus born later in the same century. I had originally dismissed that idea largely because of the above mentioned assumptions I'd made about Arianism before reading this book.
The Qur'an teaches Jesus isn't Allah, but does call Him a Word from Allah and uniquely without Sin. It does consider Him The Jewish Messiah and to have been born of a Virgin. It also teaches a general Preexistence for all Humans and so certainly implies one for Jesus as well.
Honestly there is a lot of overlap between theorizing Arian origins for Islam and the Nestorian theory, if you read Early Arianism already knowing as much about the Nestorian Controversy as I do you'll notice the Arians have some of the same concerns like Divine Impassability, which makes me rethink the possible influence of Lucian of Antioch on Arianism. A lot of these theories on Islamic Origins suggest Syriac Liturgy explains a lot about the Qur'an and Aetius could have written a Syriac Liturgy of his own or his followers could have modified an existing one.
But Nestorians are Trinitarians, so Islam is closer to Arianism then Nestorianism theologically. Meanwhile Islam's inclusion of the Virgin Birth is an issue for the Ebionite theory. And specifically Heteroousianism perhaps best explains the Islamic emphasis on condemning "Associators".
Once again I should repeat that NO the Qur'an does not say Jesus didn't die on The Cross, that is a common misunderstanding that plenty of both Muslim and Christian scholars have refuted. The Sura commonly alleged to say otherwise is merely denying that the Jews can claim credit for it.