The Jewish world in which Jesus lived was awash in Hellenism, and contemporary biblical scholars are finding its influence everywhere—including, ultimately, in the historical Jesus.
[Russell Shorto. Gospel Truth (1997), pg. 68]

Little by little modern New Testament scholarship is exploring not just the broad fact of Christian borrowing, but also details about the Pagan origins of specific Christian ideas. Here's a smattering.

What, you thought I was making this up?

Not only are Pagan-Christian similarities seen, but the reason believing scholars don't see them is also seen. See?

"It is very hard not to see extensive and basic similarities between these [mystery] religions and the Christian Religion. But somehow Christian scholars have managed not to see it, and this, one must suspect, for dogmatic reasons....
[Robert Price, Deconstructing Jesus, Chapter 3, 2000]

The Christian myths are Greek myths used to interpret Jewish ideals.

The myths it [Paul's church] generated are ultimately Greek myths, though they were used by Hellenistic Jews to rearticulate Jewish ideals.
[Mack, Burton. A Myth of Innocence; Mark and Christian Origins (1991), pg. 101]

The early Christians behaved like every other group in every other era—they adopted and adapted ideas from the culture around them.

"Richard Reitzenstein and Wilhelm Bousset were two scholars who did manage to grasp the relevance of these ancient faiths for the study of early Christianity. Their conclusion was a simple and seemingly inevitable one: Once it reached Hellenistic soil, the story of Jesus attracted to itself a number of mythic motifs that were common to the syncretic religious mood of the era. Indeed, as people familiar with the other Mystery Religions came to embrace the Christian savior, it would have been practically impossible for them not to have clothed him in all the accoutrements of his fellow Kyrioi."
[Robert Price, Deconstructing Jesus, Chapter 3, 2000]

Jesus virgin birth was borrowed from Paganism.

There is also no virgin birth story in Paul's letters, the earliest written records of Christianity, dating from just fifteen or so years after the crucifixion. While the letters are filled with passionate devotion to the figure of Jesus Christ and point quite distinctly to his death and resurrection as the centerpiece of faith ... they are utterly silent of the subject of divine birth. This part of the story had not yet been necessary.

Nor was it necessary in Mark's day, twenty years later. Inventing it became important only as Jesus expanded into a whole new world: God of the Gentiles. To the Hellenized Gentiles [Pagans] of the Empire—people who were used to their gods' having miraculous beginnings to show that, right from the start, they were different from ordinary mortals—this Jesus, this Son of God, if he were worthy of worship, ought to have a divine birth.

This is where we see a variation on the Jewish practice of creative borrowing from ancient writings, for virgin birth was not a tradition in Jewish history. No Jewish story or legend spoke of the coming Messiah being born of a virgin. But there were dozens of precedents for divine-mortal coupling and virgin birth in Greek culture. Many Greek heroes were sired by gods, either through old-fashioned penetration or something more grandiose, such as (28)... Etc. etc.
[Shorto, Russell. Gospel Truth (1997), pg. 27 - 8]

In the healing miracles the encounter of the sick person with Jesus is usually followed by a remark about the severity of the disease. The healing is either accomplished through a word of Jesus (magical terms from Aramaic are sometimes preserved; (cf Mark 5:41; 7:34), through some manipulation (Mark 8:23), or a combination of both; the conclusion tells of the success of the healing and the applause of the bystanders. All these features correspond to the standard forms of the telling of exorcisms and healing narratives in [pagan] antiquity… Nature miracles ... basic form and narrative schema .., closely correspond to those of analogous stories from the Greco-Roman world, including those that can be found in the apocryphal acts of the apostles.
[Helmut Koester. History and Literature of Early Christianity, Volume 2, Introduction to the New Testament, 2d edition. (2000), pg. 63]

The Judeo-Christian notion of Heaven was borrowed from the Greeks.

Sometime in the mid-second century BCE, it appears, the Jews found heaven. But where did they find it? Uta Ranke-Heinemann notes that the Greeks believed in immortality of the soul long before the Jews did. She points out that Josephus was quite certain where the Essene [Jewish] belief in immortality came from: "Sharing the belief of the sons of Greece," Josephus writes of the Essenes, "they maintain that for virtuous souls there is reserved an abode beyond the ocean, a place which is not oppressed by rain or snow or heat, but is refreshed by the ever-gentle breath of the west wind (76) coming from the ocean; while they relegate base souls to a murky and tempestuous dungeon, big with never-ending punishments." [Josephus, The Jewish War, 2.8.11]

So here, suddenly, and probably as a result of Greek influence on Judaism, we have heaven and hell.
[Shorto, Russell. Gospel Truth (1997), pg. 75 - 6]

Jesus death was understood as a martyr's "nobel death"

The logic behind both views of Jesus' crucifixion can be traced to contemporary conceptions of martyrdom. There is now a strong consensus among New Testament scholars that martyrological ideas were used by early Christians at some time to understand Jesus' death.….The ideas of 'vicarious, expiatory suffering, death, or self-sacrifice," to use [Harvard scholar] Williams' terms, were not Jewish ideas. A similar investigation of Greek traditions, however, turned up many analogies.
[Mack, Burton. A Myth of Innocence; Mark and Christian Origin (1991), pg. 105]

[T]he literary model for Luke's work was the ancient Greek epic .... The epic is a political and highly charged endeavor to provide a foundation story for a community. As Virgil's Aeneid is connected to the legendary events of ancient Troy...so is the hero of Luke- Acts, Jesus of Nazareth, presented as the heir of Israel's ancient prophecies. Divine providence guides the course of his activity and the activity of the apostles.... The course of events demonstrated divine legitimation for a new nation that, in spite of adversity, is destined to set the stage for a new era of history that is seen as the eschatological fulfillment of ancient prophecy.
[Koester, Helmut. History and Literature of Early Christianity, Volume 2, Introduction to the New Testament, 2d edition. (2000), pg. 51]

Mark and John's Gospels follow the old Pagan formula of an 'aretalogy,' listing the miracles and great deeds of the god.

The literary genre of another early written source for the extant gospels of the New Testament can also be recognized: one or several collections of miracle stories of Jesus, which were used by the Gospel of Mark and also by the Gospel of John. This type of literature enumerates the great deeds of a god, hero, or famous person; it must be properly designated as an 'aretalogy.'
[Koester, Helmut. History and Literature of Early Christianity, Volume 2, Introduction to the New Testament, 2d edition (2000), pg. 47]

Gospel Truth
The New Image of Jesus Emerging from Science and History and Why It Matters
by Russell Shorto

Instead of pushing his own theories and opinions, Shorto describes the spectrum of modern scholarly opinion, from Jesus-is-a-myth to the-gospels-are-history. You get the names leading scholars in each camp, with a synopsis of their opinions—a great aid to your further reading.

Absolutely the best introduction to modern New Testament scholarship, because it's written not by a scholar with an opinion to sell, but by an interested but dispassionate professional magazine writer who researched all sides of the issue and who knows how to write clearly.

The result is a clear and easy to read overview of modern New Testament scholarship, from Old Testament prophecy through resurrection and on to how modern pastors include, or ignore, NT scholarship in their daily ministry.

Out of print, but occasionally available at Amazon

Drudgery Divine
On the Comparison of Early Christianities and the Religions of Late Antiquity (1994)
By Jonathan Smith

You'll find:

	A scholar's detailed review of the Pagan-Origins scholarship from the 15th century through the early 1990s.
	Details of why the "scholarly" conclusions on each side are agenda driven. For example, there's a nice refutation of AD Nock's linguistic argument.

This book is widely quoted in the academic literature. It's got lots of good information and tons of references to the literature.

But, because Professor Smith thinks obscure is clever, the writing is terrible. This book will not make sense until you've read A.D. Nock's Early Gentile Christianity and Its Hellenistic Background.

Here's a sample >>

Jesus, admits Professor Smith quoting the Christian-borrowing scholar Loisy, was a savior-God like Osiris, Attis and Mithras. He was a god who came to earth, died, and saves, etc. etc.

from which, opines Professor Smith,
"little of value can be learned." [!!]

Professor Smith is famous for his anti-borrowing agenda—which is why he's quoted a lot.

"[Jesus] was a savior-god, after the manner of Osiris, and Attis, a Mithra. Like them, he belonged by his origin to the celestial world; like them, he had made his appearance on the earth; like them, he had accomplished a work of universal redemption, efficacious and typical; like Adonis, Osiris, and Attis he ha died a violent death, and like them he had returned to life; like them, he ad prefigured in his lot that of the human beings who should take part in his worship, and commemorate his mystic enterprise; like them, he had predetermined, prepared, and assured the salvation of those who became partners in his passion." [Quoting A. Loisy, The Christian Mystery, in: The Hibbert Journal, 10(1911 - 12), 51]
Of which Smith says:
From such a parataxis of 'likeness', little of value can be learned.
[pages 42 - 43]

Introduction to the New Testament
Volume 2
History and Literature of Early Christianity
by Harvard Professor Helmut Koester

This book is a treasure—an excellent place for new students to start and a valuable reference if you already know plenty. A clearly written, readable roundup of modern New Testament scholarship by a giant in the field.

Includes the history of who wrote what, when—and who copied from whom. Not just the canonical books, but also Q, the Gospels of Thomas, Hebrews, etc. etc. Wow.

Also details the history of which sects developed in each region, when. Not what you learned in Sunday school.

Highly recommended for any serious student.

.