Q. I have a book listing the “missing books from the Bible.” The following were named in the book. I have never seen or heard of them before, so could you tell me, are they really missing books of the Bible and if so, where would they go in the order of all the books, and are they okay to read?
Prayer of Manasseh, 1 Esdras, 2 Esdras, Psalms 151, Susanna, Bel and the Dragon, Prayer of Azariah, Jubilees, Enoch, Gospel of Philip, Gospel of Mary
You have a list of various works that come from the same communities that produced the canonical Scriptural books, but which are not accepted as the inspired word of God by Christians throughout the world. Some of them are considered to be inspired Scripture by some Christian groups, however, and that is perhaps why your list calls them “missing books from the Bible.” Several of them are found in some Bibles, but not in others, depending on the beliefs of particular groups.
I would say in general that you could read these books to get a perspective on what various people have believed at different times and in different places, but unless you belong to a Christian community that accepts them as Scripture, you should not read them in the same way that you would read the Bible. Here are some further details.
For one thing, some of these books were included in the Septuagint, a popular and influential ancient translation of the Old Testament into Greek, and as a result, various Christian communities have accepted them as canonical. The Prayer of Azariah, Susanna, and Bel and the Dragon are three additions to the book of Daniel—written in Greek, however, not in Hebrew or Aramaic like the rest of that book—that Catholic and Orthodox Christians accept as canonical. 1 Esdras and Psalm 151 are other works found in the Septuagint, and Orthodox Christians accept them, although Catholics and Protestants do not.
The Prayer of Manasseh is included in some manuscripts of the Septuagint, and Orthodox Christians consider it to be deuterocanonical, meaning that it can be read during services of worship, but it is not as authoritative as the other books in the Bible. (Please see this post for a fuller explanation of what that means.)
The books of Enoch and Jubilees are ancient Jewish works that most Jews and Christians do not consider to be Scripture, although the Ethiopian Orthodox Church and Ethiopian Jews do accept them. Jubilees is essentially a re-telling of the events of Genesis, while Enoch deals with angels and demons and events at the beginning and end of world history.
Finally, there are some books on the list that come from the first few centuries after Christ, and no Christian communities accept them as canonical. Those include 2 Esdras, the Gospel of Philip, and the Gospel of Mary.
If you do want to read these books, I would start with the ones that are most widely accepted, and I would stay away from the ones that no Christian communities accept. However, personally I would want to make sure that I had first read all of the books that all Christians accept as Scripture before devoting any time to ones that there is much doubt about.