What is a Christian? Who is a Christian? How Does a Person Become a Christian?

Jesus said you must believe I AM (John 8:24), you must be born again (John 3:3), I am the way the truth the life no one comes to the Father but by Me (John 14:6), and Jesus said be careful of false prophets who come in sheep clothing but inwardly are ravenous wolves (Matthew 7:15). What does the Bible teach a person must believe to be saved and how to become a Christian? Who is Jesus Christ? What is the Gospel for salvation?