In the early days of information study Claude Shannon postulated the idea of the signal and the noise. The signal being any discrete packet or change that conveyed information and the noise that random amalgam of data that composed nothing of informational value. Information is any difference that makes a difference. When one seriously investigates the early Christian writings it quickly becomes evident that there is a significant amount of noise that obscures, even hides, what little actual information is contained within them. Some of this noise is endemic to the times and people who composed the stories that have come down to us. Later authors of the earliest surviving manuscripts were working from different and varied sources, many if not most of those sources being oral retellings of retellings of remembered tales transmitted verbally across generations and cultures. A few of the stories may have been in written form but the almost total illiteracy of people living in the first century guarantees that the predominant method of information retention and transmission was verbal, passing stories from person to person.
As anyone who has played the game of "telephone" can attest, any information input into the beginning of the verbal, person-to-person process becomes mostly unrecognizable once it is related by the last person in the chain. Line up a number of individuals, the more the better, say five or ten people. Whisper a short tale of a few sentences to the first person. That person then whispers what he or she has heard to the next, and so on until the last person has been told. What the last person will report will bear little resemblance to the original story. Anthropologists and historians understand this, and it is one reason that actual physical and rational evidence is valued so highly. (And, it is strange that, given the certainty that people do not recall even simple events accurately and objectively, eye-witness testimony is regarded so highly by the court system.) Looked at in this way, the surviving Christian accounts of the life, times and deeds of Jesus of Nazareth are suffocatingly covered in noise, noise generated by faulty transmission, omission and as can be proven, by outright fraud, lies and deceit.
The best examples and explanations of why this has happened are found in Bart D. Ehrman's books, especially "Jesus, Interrupted" and "Misquoting Jesus". They are certainly worth your time if you have any interest at all in the problems inherent in using the Gospels as information about the life and deeds of Jesus.