There is absolutely no question that the world out of which the Christian scriptures were born was syncretistic. I believe all modern scholarship would agree that there was extensive borrowing going on between all of what we term pagan religions of the 1st century AD. The real question is: did the Apostles or the writers of the New Covenant text borrow from the religions around them in order to sell Jesus to the gentile world? Personally, I don’t see a shred of real evidence to support the theory that they did.
Consider, for example, we are told that Mithras was born of a virgin on December 25th in a cave. Some traditions even hold to his birth attended by shepherds. However, when we consider the only ‘virgin’ that Mithraism refers to is the solid rock out of which Mithras was ‘born’, we have to wonder, if the so-called scholars who try to pass this off, as a similarity to Christianity, didn’t use Christian terms to describe the Mithras in order to show similarity. Moreover, when we understand that Mithras was ‘born’ a mature adult, would anyone see the Mithric/Christian similarity on their own without the purveyors of the supposed likeness telling us, there is one? The matter of ‘shepherds’ attending the birth of Mithras must also be a joke. This god was supposed to have been born before humanity (if memory serves), so where did these shepherds come from? Another matter is that the only cave Mithras was ‘born’ in is the cavern he left behind after pulling himself out of the solid rock mountain. And, don’t forget that December 25th has absolutely no importance in early Christianity. Instead, the Christian scriptures point to the autumn, as the time of Jesus’ birth. Does anyone see anything here that would remind them of what the Apostles preached in the Gospel?
I’ve also seen on the discussion forums that Mithras was a traveling teacher who had 12 disciples. I don’t remember seeing any documentation on this, but, if we correlate the Mithras’ riding and killing the bull with the Zodiac sign, Taurus, we can theorize, he is a god of the heavens traveling like the stars do to mark out our seasons on earth. The 12 disciples then would be the 12 signs of the Zodiac. If this is the source of this idea, would anyone seriously argue for any similarity to that of Jesus and the 12 Apostles?
If we look at the New Covenant text, we would find that Christianity was simply not synchronistic at all. For example, the liberals of the Jesus Movement were the first to be persecuted by the Jewish authorities (Acts 7 & 8). About 10 years later they began persecuting the moderates, under King Agrippa and thus the apostles were expelled from Jerusalem cir. 43 AD (see Acts 12). This left only the most conservative of the Jesus Movement in Jerusalem, under the leadership of James, the brother of Jesus. Josephus tells us that he was finally executed just after Festus, the Roman procurator of Judea, died.[1] It seems the son of Annas, who was the reigning high priest at the time, took advantage of the absence of Roman authority and initiated a persecution against the conservative believers in Jesus. So, we see that Judaism of the 1st century AD rejected Jesus, showing us, though Christianity was born out of Judaism, our differences were too great for the Jews to accept us.
What about in the Diaspora? Certainly they were more liberal than the Jews in Judea, but we find that wherever Paul had gone, preaching the Gospel, the Jews rejected Jesus and even tried to kill Paul or stop his preaching by incorporating the assistance of the local government (Acts 13:45, 50; 14:2-5, 19; 17:5-9, 13-14; 18:5-7; 12-13; 19:8-9, compare Acts 21:26-30). Therefore, believers, saying Jesus was the Messiah and Savior of the world, were not believed by Judaism of the 1st century AD, either in Jerusalem or in the Diaspora.
What about the pagan religions? Was there extensive borrowing from them that would explain why Judaism was so opposed to Jesus? No, there is not a shred of evidence that would show Christianity borrowed from anyone. For example, the New Covenant text demonstrates the first believers were opposed to sorcery (Acts 13:8-12), and Christianity was opposed to the Greek pantheon, as seen in Acts 14:11-18. If Christianity was truly syncretistic, Paul and Barnabas missed a golden opportunity to make it obvious to the gentiles, who wanted to worship them. Instead of welcoming the gentiles’ willingness to sacrifice to them, Paul and Barnabas rejected their good graces and forever lost the opportunity to show how similar Jesus was to their gods. Not only was Paul and Barnabas against the pagan methods of worship, but later these same pagan worshipers stoned Paul, when they were stirred up by visiting Jews (Acts 14:19).
Later, Paul shows Christianity was not compatible with the oracle of Delphi, which was universally resorted to for advice. It seems in Acts 17 that a young girl possessed with a “spirit of divination” (Greek Pythios or Python, see G4436). Python was another name for Apollo, the Greek god of the fine arts, music, poetry and medicine. This young girl had been following Paul and Silas around Philippi, saying they were representatives of the most high God. Yet, Paul became so upset with her, passing herself off and her religious practices as compatible with what he preached, that he rebuked her spirit, leaving her without the unique abilities that represented Apollo and the Delphi oracle. If Christianity was so syncretistic, why would Paul do this? Why didn’t he take advantage of her reputation to enhance his preaching Christ to the Philippians?
Finally, we come to Artemis or Diana of the Ephesians, the queen of heaven, in Acts 19. If Christianity was so compatible with paganism, why was the Gospel causing a riot in Ephesus? The silver guild was so upset over Paul’s preaching that they caused the whole city to rise up, presumably against how un-syncretistic Christianity really was. Christian syncretism in the 1st century AD simply is not logical.
[1] Antiquities of the Jews 20.9.1