Originally posted by Br. Max
Since when were James Jude and Peter written by other than the apostles?? I think you have been reading the wrong books again. 
I don't think so. We'll take the three books individually, but the source for all this information that I'm using right now is the St. Joseph edition of the NAB (although similar info can be found in any study bible -- Oxford Study Bible, Harper-Collins Study Bible, the Teen Catholic Study Bible, the New Interpreter's Bible, the Anchor Bible, the original Interpreter's Bible, etc.)
First, realize that nowhere in any of the books does it claim Apostolic authorship. "James" and "Jude" are never said in their respective letters to be special people other than just "slaves of Jesus Christ".
James
The main reason why people think this was not written by the apostle James is that the letter seems to be specifically written in response to Paul's letters. People were apparently reading Paul's letters to mean something sort of like Amida Buddhism -- all you have to do is say Jesus' name and believe in him and you're set. Doesn't matter how much you sin after that or what you do, you're saved. So this letter was written in response to these misunderstandings.
Other points are that the Greek is excellent, much better than would be expected of any of the Apostles, and that the book never mentions his history with the Apostles or Jesus.
Jude
I'll just quote the St. Joseph here:
"Many interpreters today consider Jude a pseudonymous work dating from the end of the first century or even later. In support of this view they adduce the following arguments: (a) the apostles are referred to as belonging to an age that has receded into the past (17-18); (b) faith is understood as a body of doctrine handed down by a process of tradition (3); (c) the author's competent Greek style shows that he must have had a Hellenistic cultural formation; (d) the gnostic character of the errors envisaged fits better into the early second century that into a period several decades earlier. While impressive, these arguments are not entirely compelling and do not rule out the possibility of composition around the year A.D. 80, when the historical Jude may have still been alive."
2 Peter
According to the St. Joseph, opposition to the idea that Peter was the author of this letter began in the early church and continued to the 5th century (and beyond).
"Among modern scholars there is wide agreement that 2 Peter is a pseudonymous work, i.e., one written by a later author who attributed it to Peter according to a literary convention popular at the time. It gives the impression of being more remote in time from the apostolic period than 1 Peter; indeed, many think it is the latest work in the New Testament and assign it to the first or even second quarter of the second century."
"The principal reasons for this view are the following. The author refers to the apostles and 'our ancestors' as belonging to a previous generation, now dead (3:2-4). A collection of Paul's letters exists and appears to be well known, but disputes have arisen about the interpretation of them (3:14-16). The passage about false teachers (2:1-18) contains a number of literary contacts with Jude 4-16, and it is generally agreed that 2 Peter depends on Jude, not vice versa. Finally, the principal problem exercising the author is the false teaching of 'scoffers' who have concluded from the delay of the parousia that the Lord is not going to return. This could scarcely have been an issue during the lifetime of Simon Peter."
-Chris
