You shall not take the name of the Lord your God in vain

(William S. Plumer, "The Ten Commandments")

A great design of true religion is to bring men to habitual reverence
for God's divine majesty. The very moment men cease to treat God
as holy--that moment their worship becomes polluted.

"You shall not take the name of the Lord your God in vain;
for the Lord will not hold him guiltless, who takes His name in vain."
    Exodus 20:7

Anything relating to the true God--His being, His nature, His will,
His works, His worship, His service, or His doctrine--pertains to
God's name. This commandment extends to the state of men's
thoughts and hearts--as well as to their speech.

To take God's name in vain, is to use it in any frivolous, false,
inconsiderate, irreverent, or otherwise wicked manner. The
scope of this commandment is to secure the holy and reverent
use of all that by which God makes Himself known to His people;
and so to guard His sacred name against all that is calculated
to make it contemptible.

The manner of taking His name is to be grave, solemn, intelligent,
thoughtful, sincere, and with godly fear.

"You shall not take the name of the Lord your God in vain;
for the Lord will not hold him guiltless, who takes His name in vain."
    Exodus 20:7