What makes a Christian? When can this label be justifiably claimed and when is it a delusion to do so? Matthew 7:21 makes it clear not all who may claim the title "Christian" are in fact disciples of the Christ. Let's explore how this might be Biblically delineated.
My wife is involved in an online discussion (in a Christian homeschooling forum) about various Biblical doctrines. The one that started it all was homosexuality. Naturally Romans 1 came up. I don't know if 1 Corinthians 6 was raised, but I'd be surprised if it weren't. (Aside: While there are also Old Testament verses denouncing homosexuality, far too many so-called Christians deny the authority of the TNK, so these verses are often left out of such proofs.) Several of these so-called Christians deny the obvious, plain meaning of the Scriptures. Given today's climate within the fallen church, there are also plenty of clergy's opinions to support this denial of God's Word, and these women (the group is mostly homeschooling moms) pull out all the stops in their attempts to justify this sin.
A secondary battle ensues. These same Word-deniers then complain that God is not one of division (ref.) My wife responds with the Word of God yet again, quoting Matthew 10:34-37, Luke 12:51-53, and Luke 14:26. The Word-deniers retort, "But that applies to believers versus unbelievers." Yes.
The tertiary and most important battle begins. Can those who deny the Word really be believers of it? On the surface, obviously not. How can one claim to be a believer in gravity if the very nature of gravity is denied? These are mutually exclusive choices: believe or deny. The question then needs to be refined to just what defines a believer in the Lord, or how much of His Word can be denied before believer status is forfeited?
If Jesus is the Word (John 1:1), and denying Jesus is bad (Matthew 10:33), it would seem that denial of the Word of God is bad, too. Can a portion of the Word be denied without denying Jesus? Put another way, can a servant disobey his master in some areas and still remain in good standing as his Master's servant? Or is the nature of a servant that he is defined by his obedience to his Master? Keep in mind, we're not talking about merely imperfect obedience here, but steadfast refusal to obey particular, clear commands. It's one thing for s servant to be far from perfect in his obedience, that he unwittingly disobeys here and there but earnestly desires to obey in all things. It's completely different for a servant to stubbornly refuse to obey a particular subset of commands because he thinks the Master is wrong!
In truth, any denial of the Master's commands (i.e., His Word) is merely a vain attempt to self-justify one's sins. Persistent denial of one's sins--denial that they are indeed sinful--is, in effect, a denial of the Holy Spirit's conviction, a very dangerous prospect indeed (Mark 3:29).
In the spirit of charity, I wish to avoid being dogmatic about this doctrine, but it does seem to me, both intellectually and plainly, that steadfast denial of portions of the Word could indeed jeopardize one's "status" as a believer/follower/disciple/servant of the Lord. Without necessarily commenting on the eternal disposition of such a Word-denier, I can easily say it's laughable to call Word-deniers servants of the living Word.


Don't Be Surprised! (by Jack Donnelly)
Related and very applicable: http://www.fcet.org/pub/988
Don't fool yourself into thinking you're a believer when you, in fact, willfully and consistently fail to obey.