Answer
The word apocrypha is from the Greek word for “obscure” or “hidden.” The apocryphal gospels are so named since they were not prominent in the early church.
Matthew, Mark, Luke, and John are known as the canonical gospels because they were recognized by the early church as being accurate, authoritative, and inspired accounts of the life and teachings of Jesus. However, in addition to these four works, there were a great number of other works that purported to record other words and deeds of Jesus. These works are not authoritative or inspired and sometimes not even accurate records of the life and teachings of Jesus.
Many of the apocryphal gospels were considered by the early church to be useful but not inspired. In the years since, more works such as the Gnostic gospels have come to light, which the early church would have considered heretical. Currently, the term apocryphal gospel applies to any non-canonical early work that purports to record the life and teaching of Jesus. Neither Roman Catholics nor Eastern Orthodox nor Protestants accept any of the apocryphal gospels as authoritative or inspired. However, modern scholarship (such as applied in the Jesus Seminar) generally accepts these “gospels” as accurate records needed to give us a full picture of the life and teachings of Jesus.
Some of the apocryphal gospels are lost to us but are mentioned in other early Christian writings and would have been considered helpful though not inspired. These works include the Gospel of Andrew, the Gospel of Bartholomew, the Gospel of Barnabas, and Memoirs of the Apostles.
Some of the apocryphal gospels are the work of heretical groups that attempted to co-opt the teachings of Jesus for their own purposes. Among these works are the Gospel of Marcion, the Gospel of Thomas, the Gospel of Judas, the Gospel of Mary, the Gospel of Philip, and the Gospel of Truth. The Gospel of Thomas is probably the best-known because it was popularized by Princeton University Professor of Religion Elaine Pagels in her 2004 best-seller Beyond Belief: The Secret Gospel of Thomas.
Some of the apocryphal gospels, like the Gospel of Peter, are just bizarre. In this work, we encounter an actual talking cross.
The Secret Gospel of Mark has only recently come to light and suggests that Jesus may have had a homosexual relationship with Mark. Further investigation suggests that this find was a hoax perpetrated by Morton Smith, the man who claimed to have discovered it. However, modern critical scholarship uncritically accepted it as genuine for a time.
Because of the wide variety of teaching in these apocryphal gospels, some scholars prefer to speak of “early Christianities,” implying that there was never a single, unified, accurate, authoritative teaching about Jesus but that each group collected partial truth to suit their own needs. The group that we now call orthodox was the group that eventually gained prominence; thus, the gospels that they preferred (the canonical gospels) were accepted as authoritative while the others were suppressed. This is essentially the premise behind Dan Brown’s novel The DaVinci Code. Such theories contradict the fact that the early church received “the faith that was once for all entrusted to God’s holy people” (Jude 1:3).
On further investigation, we find that the apocryphal gospels that present some of the most divergent views on who Jesus was and what He taught were written much later than the canonical gospels. There is no evidence for the views they present in other writings of the early church. Scholars who put all the gospels on equal footing tend to be hypercritical of the canonical gospels and overly accommodating to the apocryphal gospels.
The extant apocryphal gospels are all readily available online for whoever wants to read them. For a scholarly evangelical analysis of the apocryphal gospels, we recommend Fabricating Jesus: How Modern Scholarship Distorts the Gospels by Craig Evans, and for a more popular-level explanation we recommend Chapter 1 of The Case for the Real Jesus by Lee Strobel.