Is there a way to accurately tell if a person is a Christian or not?

These are some of the things I've gathered to let you in on my thinking.

-A Christian is a follower of Christ.

-A Christian is not immune to mistakes, misinterpretations and deceit.

-A Christian is always able (has the capacity) to distinguish right from wrong?

-A Christian does not have to lead a sinless life.

-A Christian is known by his/her fruits.

-A Christian will not Always act in a Christlike way

-A Christian can learn more about God, Christianity and Life, Knowledge of these things is not instantly bestowed on a Christian.

-A Christian can be wrong on doctrine and still be a Christian*

-A Christian has a personal relationship with God, unique to every individual.

-A Christian communicates with God, but there is no standard method for how this may this will occur.

-Blasphemy is the only unforgivable sin.

*barring that Christ is God and savior, and that he died for our sins and you gotta repent.

-Alex Murphy II