When the word "purity" is mentioned, the vast majority of people assume it is short for "sexual purity." And 99% of the time they are right, because that is what the term "purity" is most used for in Christian culture.
But I often hear Christians try to define purity in broader terms, especially when they are under fire for focusing too much on teen or women's sexuality. They say it has to do with purity of thoughts and emotions as well. (The phrases "guard your heart" and "do not awaken love before its time" come to mind.) Some Christian groups, usually the more conservative ones, will try to implement guidelines in courtship to avoid emotional attachment prior to marriage. Of course that practice places people in danger of worse hurts later down the road, and, in my opinion, reveals the error in believing that avoiding heartbreak is part of purity. But in a small way I can appreciate that they are truly trying to apply their beliefs to their lives.
Because in my experience, the broader definitions of purity--the ones that incorporate more aspects of being human than sexuality alone--are proved hypocritical when put to the test. I saw this illustrated really well in a talk show I watched once. Anderson Cooper was interviewing a family who attended purity balls. The episode (I can't find the full video online) also had Randy Wilson, founder of the Colorado Springs purity ball, and Jessica Valenti, feminist author of The Purity Myth. At one point, the parents explained that purity was about much more than sexual purity, that it included all different parts of life. It sounded good in theory. But further into the show, one of the daughters spoke of the teens at her school who "were not pure." Anderson had her explain what she meant by that, and her answer was that they had had sex.
That did not surprise me, of course. If anyone is accused of being "not pure," it usually means that they have done something sexually with another person before they were married. I have never heard anyone be told they are not pure because they had sexual thoughts or got emotionally attached to someone. Sure, there will be some talk in small groups about "impure thoughts," but those are easily forgiven, and no one would ever show hesitance to date or court someone who had lost purity in one of the non-sexual-activity categories. What it comes down to is that sex is the only thing that actually matters in Christian purity. Having sex automatically disqualifies you from the "pure" group, while failing in any other area but sex keeps you in good standing.
While I personally would prefer purity to be a term used to describe the goodness of a person's heart and intentions, I also think that purity is a difficult term for any area of a person's life. It implies that perfection is expected and achievable, and I don't think it is. Purity is an all-or-nothing concept. The slightest tarnish takes away the ability to be pure at all.
I suspect that the church's obsession with sexual purity did not begin with finding purity described in the bible and then trying convey it to young people. Rather, I think the church latched on to the idea of ridding sexual sin from its young people, and found that to speak in terms of purity versus damaged goods made their message have more of an impact and was easier to talk about.
As a result, I find I do not like the word purity very much. It has lost its meaning and its sway. However, I believe there are good things in this life that can be pure. Love is one of them. I believe God is love. And I don't think love is hindered by impurities.