“Mourning” well means taking up our cross to follow Christ, as Pope Francis tells us:

“The world tells us exactly the opposite: entertainment, pleasure, diversion and escape make for the good life. The worldly person ignores problems of sickness or sorrow in the family or all around him; he averts his gaze. The world has no desire to mourn; it would rather disregard painful situations, cover them up or hide them. Much energy is expended on fleeing from situations of suffering in the belief that reality can be concealed. But the cross can never be absent” (Gaudete et exsultate 75).

Let’s love the cross, as St. Josemaría wrote: “We cannot, must not, be easy-going Christians: on earth there must be sorrow and the Cross… To find the Cross is to find happiness: it is to have found you, Lord!” (The Forge 762, 766). To flee the cross is to flee Christ; to embrace it is to embrace Christ, honoring God’s name, as St. Paul emphatically says:

“Have this mind among yourselves, which is yours in Christ Jesus, who, though he was in the form of God, did not count equality with God a thing to be grasped, but emptied himself, taking the form of a servant, being born in the likeness of men. And being found in human form he humbled himself and became obedient unto death, even death on a cross. Therefore God has highly exalted him and bestowed on him the name which is above every name, that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father” (Philippians 2:5-11)

Embracing his cross, Christ exalted God the Father and moved the Father to bestow on him the name above every name: Jesus. God is calling us to do the same, to graciously accept life’s sufferings—as a sharing in Christ’s atonement for our sins. This will help us to see Christ in everything in our lives and earn us a great name. We will revere God, his name, Christ’s name, and honor the great names of Mary and the saints. A failure to embrace the cross is a failure to love.

Although using God’s name in vain may not be a mortal sin, it always hurts our relationship with him. For example, consider a man who shouts out his wife’s name every time something bad happens: he hits his thumb with the hammer and shouts out, “Oh Marylu!”, or he breaks a glass… “Marylu, not again!” etc. This wouldn’t kill their relationship but it certainly would hurt it. Likewise, if every time something bad happens we use God’s name in vain—perhaps we miss a basketball shot and shout “Oh Christ…,” — it is as if we were saying: “Christ, if you wouldn’t have moved the hoop, the ball would’ve gone in”. This is usually not a mortal sin, as it would if God’s name were used with hatred or contempt. Using God’s name in vain or with slight irreverence is still offensive, hurting our relationship with him.

When you see God’s name carelessly or poorly used defend it and mourn by making acts of reparation or atonement.

Cussing (the use of expletives and “four letter words”) doesn’t entail using God’s name in vain, but is a way to blame others for our suffering by making them suffer with us, saying something that would hurt or disgust them. Thus cussing is a lack of longsuffering (suffering with patience) that leads to a lack of charity.