Towards the end of his life, Buddha said: "I am still seeking the truth." Jesus said: "I am the way, the truth, and the life." He is everything! There is nothing more to add: His teachings and life are guiding for all of humanity. If we follow Him, we will never go wrong. 

We constantly need to adjust ourselves to Him. He left us "an example, that you should follow His steps" (1 Pet 2:21). Jesus's teachings are the main ingredient in my theology. Jesus said: 

"My food is to do the will of Him who sent Me, and to finish His work."

John 4:34

Jesus came from the Father and did His will exactly. What He said and did is pure truth. He is the Alpha and the Omega, the beginning and the end, and everything in between. You can follow Him without hesitation. All extrabiblical writings should be taken with a grain of salt. I believe that the Bible, as it was originally written, is infallible. The Bible does not only contain God's word, it is God's word to us humans. 

"All Scripture is given by inspiration of God."

2 Tim 3:16

Therefore they are called "The Holy Scriptures" (1 Tim 3:15). They are holy because they are thoughts and words that God has spoken to us through His chosen men and women of God. The Bible is therefore a holy book.