To the pure all things are pure, but to those who are defiled and unbelieving nothing is pure; but even their mind and conscience are defiled. (Titus 1:15)
If you have pure thoughts, you will experience pure deeds. All sin begins in the mind. There is no such thing as reflex sin. If you hit your thumb with a hammer and explicit language comes forth, it is because it was present. An indiscretion of the tongue begins with an indiscretion of the mind. The vulgarity of language is only coarse to the vulgar mind. A pure heart and mind can purify the grossest of words. Nevertheless, even the purest of words are polluted by the unbelieving and defiled mind. Actions truly speak louder than words. It is not so much what a person says as what a person does. Even what a person does is measured by what God sees, not by what man sees. Remember, man looks at the outward, but God looks at the heart. Therefore, if your thoughts are pure and your conscience clear your actions will follow suit.