Conservative, liberal, socialist, anarchist, libertarian, feminist, activist, independent, Calvinist, Arminian, Neo-Reformed, Roman Catholic, red-letter, black-letter, purple-letter?
It could be that this is just a short-hand way of efficiently describing our stream, tribe, or beliefs. It certainly is more convenient to use jargon. It also could be that you're trying to distinguish yourself and your tribe from the rest of Christians - a kind of "You don't know me, I don't fit in your boxes" by creating new boxes.
I fear that something much deeper is at play, though.
There are at least two major problems that our language and descriptions reveal. First, the vast majority of the time I have heard people speak this way, they are much more passionate about the modifying word than they are about Jesus. For instance, a politically-defined Christian is often much more concerned to evangelize their perspectives on partisan policy issues, spreading the gospel of their political ideology, than they are about the gospel of Jesus Christ. Even our theological modifiers show the same problem. If someone leads with I'm a Calvinist, or Arminian, they are almost certainly going to spend more time passionately arguing for their view of election and predestination than they are passionately talking about their love for Jesus. This is a problem.
The second problem is the desire to distance oneself from all other Christians. This shows a tribalistic mentality, that someone is more concerned with the flourishing of their narrow theological band of brothers and sisters than the flourishing of the gospel of Jesus Christ. If one's theology becomes so narrow that they are trying harder to convert people to their tribe than to life in Jesus, they're on dangerous ground.
Both of these areas reveal the one, ultimate problem: identity. So often when a modifier is attached to "Christian" it belies an identity in something other than Christ. It is not to Him that the ultimate allegiance lies, but to a version of Jesus that is shaped in our image and likeness. Oh sure, we can be experts in slapping all kinds of spiritual language onto it, even talking about how God has revealed these things to us. By nature, though, it is a way to exclude and diminish others, implying that they don't have access to the same revelation.
Make Jesus Your Favorite
It's not that these modifying words are unimportant, but it's worth asking if they are essential. To be a Christian is to believe that Jesus carried out God's mission of redemption by living the life we are incapable of living, dying in our place for our sin, being raised from the dead to conquer sin and death, and ascending into Heaven where He intercedes on behalf of His people now. To be a Christian is to believe that Jesus dying words, "It is finished," actually do mean that the work was done and that nothing can be done to add to it or take away from it.
Why look for a way to add to Jesus?
This good news that we call the gospel informs our perspectives and actions. It should inform our politics and political engagement. The gospel should inform and shape our perspectives on life and our priorities. The gospel should be at the center of our theological framework, breathing life into further study to understand God's character, especially through His Word. No one tribe has a corner on the gospel.
There is diversity in Christianity. It is critical that we do the hard work of determining what is primary and secondary. In our church we talk about "open-hand" and "closed-hand" issues. Closed-hand being the things we will cling to and fight for - that which is essential for the gospel and salvation. Open-hand issues are those things for which we have beliefs and practices, but we recognize that there is diversity among God's people and choose not to major on them. Our identity, though, is to be found in Christ alone.
If you are in Christ, everything else is secondary or tertiary. May our lives and our language reflect that for His glory. Find your identity in Him. Make Jesus your favorite and stop modifying your self-description with lesser gospels.