Wikipedia:
A Christian (pronounced /ˈkrɪstʃən/ ( listen)) is a person who adheres to Christianity, an Abrahamic, monotheistic religion based on the life and teachings of Jesus of Nazareth, who Christians believe is the Messiah (the Christ in Greek-derived terminology) prophesied in the Hebrew Bible, and the son of God.[1][2] Most Christians believe in the doctrine of the Trinity ("tri-unity"), a description of God as Father, as Son, and as Holy Spirit. This includes Roman Catholicism, Orthodox Christianity, and the vast majority of Protestantism. A minority are Nontrinitarians.
The term "Christian" is also used adjectivally to describe anything associated with Christianity, or in a proverbial sense "all that is noble, and good, and Christ-like."[3]
In John 15: 1-5, Jesus says this:
1 I am the true vine, and my Father is the husbandman.
2 Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit.
3 Now ye are clean through the word which I have spoken unto you.
4 Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me.
5 I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing.