A Christian’s viewpoint on the Gothic / Emo movement should be avoidance of the culture’s dark attitudes while still loving those involved in it. Yes, there are definitely certain aspects of the Gothic and Emo subcultures that are incompatible with Christianity, but no more so than similar aspects of mainstream society. These particular communities identify themselves with artistic darkness—darker clothing, darker writing, darker music. In fact, both Goth and Emo originally (and presently) referred to specific music genres with punk roots before they were considered personal styles.
While it may seem that all Goths or Emos share the same level of devotion to darkness, each individual will have his or her own preferences about which aspects he or she chooses to partake in. What is important to understand is that, for most Goths / Emos, it is a "dark" aesthetic they subscribe to, not necessarily darkness as it relates to evil. Wearing black clothing is not inherently sinful. Enjoying art that emphasizes black is not inherently sinful. There is nothing evil about the color black. The Gothic / Emo subculture is no more inherently wicked or wrong than any other subculture. Condemnation of Gothic / Emo adherents is usually brought on by a knee-jerk reaction to their uncommon appearance, but that condemnation is a sin (John 3:17). As followers of Christ, we need to be beyond that (John 7:24). Like all of us, they are people who desperately need Christ in their lives. Every human being is on an equal level of sin as far as God is concerned (Romans 3:23), and being a part of the Goth or Emo subculture makes no difference in terms of eternal security.
Can Goths or Emos come to faith in Christ and still involve themselves in a dark aesthetic? If they are glorifying Christ in what they do, yes (1 Corinthians 10:31). We cannot impose our own spiritual maturity, personal convictions, or style choices on another person—no matter how strange they may seem to us. Let the Christian Goth / Emo wrestle with his/her ideologies as God brings them out for scrutiny. What we can do is provide support, counsel, and love as the Holy Spirit guides us in our relationships (John 16:13).
Conforming to the image of Christ does not mean you must stop wearing black and dress like every other upper-middle class American / Western European. That has nothing to do with Christianity. It does mean, though, that a Goth’s or Emo’s mindset and dark attitudes will undergo a change, even if the black clothes and attraction to darkness might remain to a certain extent. It is the heart that God searches (1 Chronicles 28:9), thus the heart is what we must first look at ourselves, whether it be among Goths, Emos, punks, gamers, jocks, etc.