Sometimes you make interesting discoveries about words. I was thinking about what the opposite of purity was. One strong possibility was defilement. It made sense as according to the little dictionary of synonyms and antonyms that I had had since school days the antonym of defile is purify.
The next thing I wanted to check is where does the word defilement come from. That is when it became interesting. There are two listing in my dictionary for the word defilement. One was what I expected and it appeared that the root of the word was foul. Hence the idea of to defile meaning to foul to pollute or to make impure. One was totally unexpected. It was linked to the idea of a file of soldiers. The root of this use of the word was fil or thread. Defilement in this sense meant to march off in a file. Think of marching single file along a narrow path through a gorge.
There was some sense in how these words have developed. However, one thing that struck me as I read the entries in the dictionary was that there was something called enfilement. This referred to tactics that were used to protect soldiers that were positioned in a line and therefore were particularly vulnerable to certain forms of attack.
Hold on a moment there is more similarity here than you might think. Defilement leaves soldiers in a position where they are vulnerable and it is harder to carry out their role of defending themselves and others. Defilement i.e. lack of purity leaves the church and those who are part of it in a position where they are vulnerable and it is harder to carry out their role of defending themselves and others. Very strange!