Testimony
To you, how reliable is a person's testimony? What factors do we need to take into account?
The Church of Jesus Christ of Later Day Saints states that God and Jesus (Why they separated in their communication I'll never know) came to Joseph Smith one night and told him about the future of Christianity, an angel then came and directed him to find some golden plates which he translated with some friends- Mormonism was born.
This statement is based on the testimony of Smith, three witnesses and another eight witnesses, all who testify to have seen these Golden Plates and maybe even the angel. Is this testimony reliable? Smith made himself President of a Church and became quite powerful, also, many of the 3,8 witnesses were his relatives who also gained...however some of the witnesses fell out with Smith and subsequently were kicked out the Church...but they never retracted their testimony...does this add to its reliability?
In court, Mr. Peter Anderson, a black mechanic was on stand for murder, the key witness of the prosecution was a member of the Ku Klux Klan and obviously hated blacks- however he did tell the truth under oath and Mr. Anderson was indeed guilty of the murder...however...would you believe the key witness? Or would you assume his testimony unreliable due to his membership of the KKK?
In both these examples, the testifiers have something to gain so it is understandable that their testimony would be treated with suspicion.
However, take the apostles, who post-Christs' death wandered the known world spreading Jesus' gospel (writing it down was a Roman thing and it was common for stories to be spread by word of mouth though as we see from some letters they could write and did) anyway they apostles didn't really have a comfortable life running from the Roman Empire but they did it anyway, indeed they were killed for spreading these words...but not just killed, Crucified one of the most gruesome painful deaths imaginable. Why? They didn't gain very much, didn't profit from the riches that their Church would eventually get...so is their testimony reliable? They choose extremely painful deaths to spread what they believed to be the Word of God...religious fanatics perhaps? Though...they had known Jesus in life, and seen him die...if their testimony is false...who made up the resurrection, why and why were they willing to die for this lie?
Ok, final example, your friend comes to you and tells you something that you find hard to believe...say the world at the back of the wardrobe...is the person mad...you'd probably think they must be but upon closer inspection you could conclude they're not, they don't lie...so must we assume their testimony is correct?
If their is no motive for lying, or in fact an incentive not to lie why would they?