Note: Chastity in the sense of the “evangelical counsels” refers to temperate control of sexual desire and function. For those in religious orders and for other unmarried people it expands to avoiding all sexual activity (celibacy), but for most Christians (i.e., the married ones) it means remaining faithful to one’s marriage vows and avoiding sexual temptations. Martin Luther talked about the same thing in his Small Catechism explanation of the 6th Commandment: “…so that we lead pure and decent lives in word and deed, and each of us loves and honors his or her spouse.” But as you can see in this quote, chastity is closely related to abstinence and sobriety.

Quote:
“Chastity is the virtue which excludes or moderates the indulgence of the sexual appetite. It is a form of the virtue of temperance, which controls according to right reason the desire for and use of those things which afford the greatest sensual pleasures. The sources of such delectation are food and drink, by means of which the life of the individual is conserved, and the union of the sexes, by means of which the permanence of the species is secured. Chastity, therefore, is allied to abstinence and sobriety; for, as by these latter the pleasures of the nutritive functions are rightly regulated, so by chastity the procreative appetite is duly restricted.”

Source: Melody, John. “Chastity.” The Catholic Encyclopedia. Vol. 3. New York: Robert Appleton Company, 1908.