Zoroaster was a Persian prophet, though some (perhaps erroneously) refer to him as a god. While some scholars claim he was first worshipped around 1700 B.C., the earliest existing references to Zoroaster come from around 600 B.C. However, almost everything we know about Zoroaster come from texts written over 300 years after Jesus walked the Earth, and the earliest existing copies of these texts are from the 13th century. This creates a serious problem for those claiming Christianity "borrowed" from Zoroastrism, since the evidence suggests that it was the other way around, that the Zoroaster character was changed to become more like Jesus in post-Christian times.
1. Zoroaster was born of a virgin and "immaculate conception by a ray of divine reason."
Zoroaster's mom was married when she gave birth to him, and there's nothing suggesting she was celibate while married. The "ray of divine reason" was apparently a purely spiritual thing, and Zoroaster's body actually was created the usual way.
2. He was baptized in a river.
Zoroaster receives a revelation while on the banks of a river. That's the closest parallel to be found.
3. In his youth he astounded wise men with his wisdom.
Sort of. At age 7, he was put under the care of magi, who he frequently argued with. Later, the magi had him imprisoned, but he was freed after he made the legs grow back on a horse.
4. He was tempted in the wilderness by the devil.
There is a parallel in the Zoroaster story to Jesus' temptation, and, yes, it does apparently predate the Jesus story by a couple hundred years. However, Zoroaster's "temptation" wasn't by the "devil" (in Zoroastrian literature, Ahriman) and it may or may not have been in the wilderness (the texts don't say). Zoroaster is tempted by a demon, not by Ahriman himself. And his temptation doesn't involve turning stones to bread or leaping from towers, just dialogue between Zoroaster and the demon.
5. He began his ministry at age 30.
True, but the earliest reference to his being thirty is post-Christian.
6. Zoroaster baptized with water, fire, and "holy wind."
First of all, there's no reference to Zoroaster baptizing with any of these things. Second of all, there's no Biblical reference to Jesus baptizing with any of these things! Is the fact that neither of them do these things a parallel?
7. He cast out demons and restored the sight to a blind man.
There's no reference to Zoroaster casting out demons, and the earliest reference to his giving eyesight to the blind is from the 10th century A.D.
8. He taught about heaven and hell, and revealed mysteries, including resurrection, judgment, salvation and the apocalypse.
Zoroaster did teach about heaven and hell, and resurrection into a non-dying body. Judgment is done by other gods, but with Zoroaster pleading the case of those who are faithful to him, though, unlike with Christianity, the faithful are not automatically saved. Salvation is achieved by works alone, unlike Christianity. And the apocalypse Zoroaster spoke of was a flood of molten metal. Sounds like a pretty good comparison, huh? However, most of this is from post-Christian writings. Also, most of these subjects begin on the Bible's Old Testament, which predates the earliest Zoroastrian references by several hundred years.
9. He had a sacred cup or grail.
First of all, Zoroaster did not have a sacred cup or grail. Second of all, Jesus (at least according to the Bible) did not have a sacred cup or grail. The Christian "holy grail" is believed by some to be the cup Jesus drank from at the last supper, and others say it was a chalice that collected Jesus' blood at the crucifixion. But as far as its being 'sacred', the Bible makes no such claim. This is a medieval non-Biblical legend.
10. He was slain.
Ummm...okay. So were Caesar, Abraham Lincoln and John Dillinger. Is this supposed to be significant? Let's look at how Zoroaster was slain and see if there is any comparison to how Jesus was slain, shall we? One story has him murdered at the age of 77 by a wizard. Another has him killed in battle. Both of these stories date from the 15th century at the earliest.
11. His religion had a eucharist.
Since they believe in salvation by works alone, why would they have a eucharist? The closest thing they have to a eucharist is a ritual involving the haoma plant, but they don't claim the plant is Zoroaster's body or blood. Besides, the earliest reference to this ritual is post-Christian.
12. He was the "Word made flesh."
No reference to this, implicit or explicit.
13. Zoroaster's followers expect a "second coming" in the virgin-born Saoshyant or Savior, who is to come in 2341 CE and begin his ministry at age 30, ushering in a golden age.
First, there's nothing about his being thirty, or of the redeemer being Zoroaster himself. Even the religion disagrees with itself on exactly what's going to happen, though the date of 2341 CE is given (although how this date compares to Jesus, I have no idea). A pre-Christian text (around 400 B.C.) refers to a single redeemer who ushers in a golden age. Later post-Christian texts suggest there will be three redeemers conceived by virgins who bathe in a lake in which Zoroaster's sperm is being divinely preserved. One of these redeemers will eradicate death. Only the one pre-Christian reference could be considered valid, but that one mentions nothing about the return of Zoroaster himself or virgin birth.