CCC 2155
Life in Christ›SECTION TWO THE TEN COMMANDMENTS›CHAPTER ONE YOU SHALL LOVE THE LORD YOUR GOD WITH ALL YOUR HEART, AND WITH ALL YOUR SOUL, AND WITH ALL YOUR MIND›II. Taking the Name of the Lord in Vain
The holiness of the divine name demands that we neither use it for trivial matters, nor take an oath which on the basis of the circumstances could be interpreted as approval of an authority unjustly requiring it. When an oath is required by illegitimate civil authorities, it may be refused. It must be refused when it is required for purposes contrary to the dignity of persons or to ecclesial communion.