Agedp1953 refers to the efficacy of eyewitnesses, which I believe you cannot trust implicitly.
Some of you may remember the shooting by police of Jean Charles de Menezes on the London underground in 2005. This man was believed to be a fugitive involved with previous bombing attempts. I was at home that day when the news came in and i listened to the story unfolding. The news teams were interviewing eyewitnesses at the station.
It transpired that Mr de Meneze walked into the station, picked up a free newspaper and used his oyster card to go through the barriers. One eyewitness said Mr de Meneze leapt over the barriers, another said he had explosives around his body, others said that the police challenged him. It later transpired that a policeman had leapt the barriers and that Mr de Meneze had not been challenged.
You can see from the above and the subsequent investigations that people believed they saw something, which in fact they didn't and that accounts between eyewitnesses vary.
Given that 2000 years have elapsed since the birth of Jesus, the delays in writing the gospels, omissions, changes made because some people disagreed with or did not like what was written, errors in translation, printing errors, how can anyone be sure that what they are reading in the Bible is truly accurate?