Well, the main reason of my inquiry was to understand why a person from another religion would believe in a Bible. What makes Bible so Special? Since it was written by men in different times and by multiple men and for some books are written by unknown authors. What was the criteria and how authentic were those writers?
I think your sort of missing something. Christians do not believe in the bible but in Jesus. It is, however, true that christians believe that the bible is theologically valid and truthful but it is second to God and the teachings of the apostles. An account given by Papias of the gospel of Mark "And the presbyter said this. Mark having become the interpreter of Peter, wrote down accurately whatsoever he remembered. It was not, however, in exact order that he related the sayings or deeds of Christ. For he neither heard the Lord nor accompanied Him. But afterwards, as I said, he accompanied Peter, who accommodated his instructions to the necessities [of his hearers], but with no intention of giving a regular narrative of the Lord's sayings. Wherefore Mark made no mistake in thus writing some things as he remembered them. For of one thing he took especial care, not to omit anything he had heard, and not to put anything fictitious into the statements" We only have a fragment of Papias writing though.
People from another religion would believe in the bible if they are convinced that it teaches the truth and believing is beneficial to them. The main two principles of christianity are love your God with all your heart, mind and soul and love your neighbor as yourself. Once someone is convinced of those two, he or she should be able to convince themselves of the teachings of the church. A good example is Justin. He tells his conversion as follows <a href="http://www.ccel.org/fathers2/ANF-01/anf01-48.htm#P4043_787325re">here</a>
The authors of the bible were well respected and their quotes are found in the father's of the church who knew the disciples. Here's what Polycarp, who died for Christ, said of Paul, "These things, brethren, I write to you concerning righteousness, not because I take anything upon myself, but because ye have invited me to do so. For neither I, nor any other such one, can come up to the wisdom21 of the blessed and glorified Paul. He, when among you, accurately and stedfastly taught the word of truth in the presence of those who were then alive. And when absent from you, he wrote you a letter,22 which, if you carefully study, you will find to be the means of building you up in that faith which has been given you, and which, being followed by hope, and preceded by love towards God, and Christ, and our neighbour, "is the mother of us all."23 For if any one be inwardly possessed of these graces, he hath fulfilled the command of righteousness, since he that hath love is far from all sin."
What if some one come up and write their own book of Bible? what is there to stop him/them? isn't what happend before?
The books of the bible were collected in the canon because these authors had proven themselves and were apostles. We don't expect that there will be any new revelation because our Lord said at the last supper, "There is no greater love than this." Thus any other revelation would be expounding on truths that are already contained in the bible.
