Consider: A believer, a follower, a student, a disciple, an apostle, a prophet, a saint, and a martyr. Each of these words has been used to describe a Christian, the bible tells us some are babies and others are more mature, the real test is with God Himself. The Word tells us that we will know them by their fruit. The word also says the world will know us by our love for each other. Love, commitment, focus, sacrifice, suffering are all part of the formula.
However, I would never dare say that this is or that is not a Christian, the reason is the warning against judging others. I fail everyday, I think a real Christian repents regularly and has a true Travail of Soul. Please study that phrase; I learned it in a book I am reading called Azusa Street by Frank Bartleman. That experience could be a very important experience for a true believer, some call it born again, and it is painful, humbling, tearful and tiring. I hope this is useful to you, God Bless you in your walk.
One last though, it is also relationship with the living God, experiencing the annointing of the Holy Spirit, it is to hunger and thirst for righeousness. As A.W. Tozer wrote, It is a Pursuit of God.
I offer this as my understanding and experience, I fail everyday, but I know whom I serve, I believe that Jesus Christ is the Author and finisher of my faith. I trust that he is able to finish what He started in me. I am his bondservant. Moreover, as Job said Even if He slays me I would still serve Him.
David Michael Paul