Inconsistencies

We don't know that Jesus said it do we?

Well for starters:

John 14:6 (King James Version)

Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me

Which is it? Is the Bible a reliable or unreliable witness to what Jesus said?

If you wish to claim some passages as reliable and others suspect, what do you use to decide which is which?