Some think a Christian is one who necessarily believes certain things. That Jesus was the son of God, say. Or that Mary was a virgin. Or that the pope is infallible. Or that all other religions are all wrong.
Some think a Christian is one who necessarily does certain things. Such as going to church. Getting baptized. Giving up liquor and tobacco. Reading the Bible. Doing a good deed a day.
Some think a Christian is just a nice person.
Jesus said, "I am the way, and the truth, and the life; no one comes to the Father, but by me" (John 14:6). He didn't say that any particular ethic, doctrine, or religion was the way, the truth, and the life. He said that he was. He didn't say that it was by believing or doing anything in particular that you could "come to the Father." He said that it was only by himby living, participating in, being caught up by the way of life that he embodied, that was his way.
Thus it is possible to be on Christ's way and with his mark upon you without ever having heard of Christ, and for that reason to be on your way to God though maybe you don't even believe in God.
A Christian is one who is on the way, though not necessarily very far along it, and who has at least some dim and half-baked idea of whom to thank.
A Christian isn't necessarily any nicer than anybody else. Just better informed.