What do we know about this first rank personage who was Apollos?
Our record presents him as an eloquent Jew versed in the Scriptures, a native of Alexandria. In his hometown of Alexandria, the young Jewish scholar had therefore devoted himself ardently to the study of the Scriptures. He also had to delve into the writings of the most erudite of his co-religionists in Alexandria, particularly the religious philosophy of Philo. On the other hand, it is said that Apollos was familiar with the baptism of John. Another note from the historical aspect that we have already quoted several times (Acts 19:1-7) speaks of a group of twelve disciples of John existing in Ephesus, and the little regard these disciples of John have for the Holy Spirit has allowed us to see in them authentic Mandeans. It was at Ephesus, therefore, that there presented itself, to a spirit curious about things of religion as Apollos was, the opportunity of learning about the baptism of John, of making contact with the Mandean religion.
The Mandeans had to communicate to Apollos their hostile feelings toward the Law, but their doctrine and especially their rites do not seem to have detained the young scholar eager for emancipation for long. He became more interested in "the things concerning Jesus," and even set about teaching them. Later, he would be considered the leader and inspirer of one of the three great parties that would divide the Church, and he would be named without objection with Peter and Paul. We know the tendencies of the party that referred to Peter, we also know those of the party that referred to Paul. What could have been the doctrine of the party inspired by Apollos?
Apollos had to be the agent, or at least one of the principal agents through which the influence of philonism was exerted upon Christianity. On the other hand, he had just turned his back on Mandeism. His doctrine must therefore have been profoundly marked by the philonic influence and at the same time fighting Mandeism, while inspiring from it, according to the methods of the religious controversies of the time, several of its fundamental elements.
We possess a writing which manifests to the utmost degree those traits which were to characterize the party of Apollos: it is the Gospel of John.
At several points, the author of this Gospel seems to discuss and explain himself with the writings of Philo, appropriating what can be assimilated to his own theology, rejecting and refuting what seems to him contrary to the truth. Thus when he twice declares that no one has ever seen God, he not only rejects the authors of the apocalypses who claim to have contemplated God on his heavenly throne, but also the theory of the vision of God in the rapture, which occupies an important place in Philo's system. The name Israel, according to Philo, would mean ho horôn théon, "the one who sees God." 
The party of Apollos thus seems no stranger to the Joannite phase of early Christianity, which comes to interject itself between the Pauline and Catholic phases.
The polemic we found in the Gospel of John against revelation by the Holy Spirit is easily explained among the sectarians of the former Mandean Apollos.
Thus the Joannite Apollos would have become the inspirer of Joannite Christianity. There would therefore have been here the substitution of John the Apostle for his namesake the Mandean revelator, in the same way that there was, for Revelation, the substitution of John the Apostle for his other namesake the Jewish prophet and visionary.
Let us return to the events of Ephesus:
At Ephesus, Apollos, turning away from Mandeism, but having retained of it the profound contempt for the Law that characterizes it, takes the side of the proselytes who rebel against the law of Noah, against the prohibition of blood that the decree of Jerusalem wanted to impose on them. He provoked the secession from the synagogue and thus founded a new independent religion, within which he could henceforth, in all freedom, teach the "way" and the "things concerning Jesus".
That religion, we know: a religion whose roots lie in the proselyte groups of the dispersion, but whose followers differ from the other proselytes on this crucial point: since their establishment as an independent community, they have always been refractory to the prohibition of blood. There they are taught the "things concerning Jesus." Soon, this new religion will also make Jesus a revelator descended from heaven to earth, after the type of the revelator John of the Mandeans. It will fabricate a biography of him. And it will also attribute to him its own origin, it will make him the initiator of its rites, the inspirer of its doctrine and the founder of its community.
That religion is the Christian religion.
Thus it will create the myth of its establishment, the ritual account of its origins, which is currently delivered in the Gospels and the non-documentary portions of the Acts of the Apostles.
(translated from The Mandeans and Christian Origins
, my bold)
Hence, against the Jews of the original anti-Christian Book of Revelation, and against the anti-YHWH Mandeans, Apollos had usurped from both
them their view of John the Baptist (the Jews had him as their prophet, while the Mandeans had him as a Gnostic anti-YHWH revealer), by christianizing him as our John the Baptist.