The Quran includes the Sabians as Children of Scripture along with Christians and Jews. I thought it odd because they're essentially Mandaeans gnostic duelists linking into Zoroastrianism and therefor un-orthodox. The Sabians were also equated with the Elcesaites - a Jewish Christian sect - that looks to tie in with Nazarenes and both herald John the Baptist over and above Jesus Elcesaites - WikipediaThere is a debate over the "Nazareans" in the Quran (Nasara in modern Arabic). It could be related. The main criticism to this possible connection is the long period between the 1st and 6th/7th century (the plague of Justinian and related phenomena must be still going on) so that the Quran redactors shouldn't know about these "un-orthodoxe Christian". If on the other hand one consider like Heinsohn that the Roman 1st century history belongs to much later...
Edit: Attached is a paper I found about the Nazorean term in the Quran
I don't know how much stock is put into Blavatsky, but she states http://theosophy.ph/encyclo/index.php?title=Nazarenes
Helena P. BLAVATSKY wrote that the Nazarenes were Jewish Gnostics who “were the descendants of the Scripture nazars, and whose last prominent leader was John the Baptist” (IU II:132). The Nazars, or NAZARITES, were a group of Jews who dedicated themselves to their religion, such as Samson and Samuel. They were also called the Baptists or John’s Christians, and often identified with the Sabians and EBIONITES. She wrote, however, that the later Nazarenes recognized only John the Baptist, and did not consider Jesus Christ as the Messiah. (Theos. Glossary, “Nazarenes”). “The true followers of the true Christos were all Nazarenes and Christians, and were the opponents of the later Christians” (SD I:198 fn). The scripture of the Nazarenes was the CODEX NAZAREUS
Also, I remember reading in the Templar Revelation by Picknett and Prince that there are no records of the place "Nazareth" until after the battle of Masada in 70AD, I don't know if thats relevant? Its curious though, that Nazareth is today the capital of the predominantly Muslim Arabs of Israel Nazareth - Wikipedia
Nazareth is known as "the Arab capital of Israel".