What would an error in the bible even show?

[Undeceived]

Bingo. The earliest gospels were written decades after the death of Jesus, so the writers relied on the memorization of oral stories, each other's gospels, and their respective sects and their own beliefs. The earliest canonical gospel, the Gospel of Mark, is dated around 70 AD, forty years after the death of Christ. Forty years of oral stories is effectively playing a lifelong game of telephone.

If the Gospel accounts are indeed true, and there was an explosion of converts, there existed no immediate need to write a report. Preaching in synagogues was the best way to spread word. Once churches began forming in Gentile nations without a constant eyewitness around for guidance, people needed a text to refer to. Enter the Gospel of Mark--written factually and in a manner that Gentile Romans would understand. Mark explains Jewish customs (7:2–4; 15:42), translates Aramaic words (3:17; 5:41; 7:11,34; 15:22,34) and has a special interest in persecution and martyrdom (8:34–38; 13:9–13)—subjects of special concern to Roman believers.

Following Mark’s Gospel, Matthew sets out to prove to young Jewish readers that Jesus is their Messiah. He has more quotations from or allusions to the OT than any other NT author. He traces Jesus’ descent from Abraham, does not explain Jewish customs, and uses Jewish terminology like “kingdom of heaven” and “Father in heaven,” where “heaven” reveals the Jewish reverential reluctance to use the name of God. He wants Jews born after Christ’s ministry to not only hear the report but what the life of Jesus means.

Luke’s Gospel is directed specifically to Theophilus (1:3). The use of “most excellent” with the name indicates an individual, and supports the idea that he was a Roman official or at least of high position and wealth. He was possibly Luke’s patron, responsible for seeing that the writings were copied and distributed. Such a dedication to the publisher was common at the time. Luke may not have considered putting pen to ink at all until Theophilus’ offer to fund the operation. The Gospel is, in particular, written to strengthen the faith of believers and to answer the attacks of unbelievers. It was presented to displace some ill-founded reports about Jesus (see 1:1-4). Luke wanted to commend the preaching of the gospel to the whole world.

John’s dedication to showing who Jesus is through lengthy discourses and “I am” claims suggest a heresy going on at the time. Gnosticism arose about then, questioning the divinity of Christ and who Jesus said he was. John plainly states, “but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.” With more doubters came a firmer response.

Each of these Gospel writers had a clear purpose in mind, and it was not simply “to write it down.” They saw ignorance. They saw denial. And they answered with what they knew to be the truth. Matthew and John had the added bonus of being eyewitnesses, meaning they did not have to rely on “memorization of oral stories.”