In His NAME

 "In the name of the Father, and of the Son, and of the Holy Spirit"

When we begin to pray, we do so in God's NAME. It is not under our own will and authority that we act:  rather, we do so in obedience to God and the promptings of His most Holy Spirit.  

The 2nd commandment of the decalogue treats of sins of blasphemy:

You shall not invoke the name of the LORD, your God, in vain. For the LORD will not leave unpunished anyone who invokes his name in vain. (Exodus 20:7)

The key word here is "Invoke": blasphemy is a much broader sin than simply not swearing or using ejaculations that include sacred words. If we claim to be Christians or Catholics and to speak AS such, we must be very mindful of what we do or say. We are meant to be light to the world, and if we come in His Name we must tread with care.

The catechism states:

2148 Blasphemy is directly opposed to the second commandment. It consists in uttering against God - inwardly or outwardly - words of hatred, reproach, or defiance; in speaking ill of God; in failing in respect toward him in one's speech; in misusing God's name. St. James condemns those "who blaspheme that honorable name [of Jesus] by which you are called."78 The prohibition of blasphemy extends to language against Christ's Church, the saints, and sacred things. It is also blasphemous to make use of God's name to cover up criminal practices, to reduce peoples to servitude, to torture persons or put them to death. the misuse of God's name to commit a crime can provoke others to repudiate religion. Blasphemy is contrary to the respect due God and his holy name. It is in itself a grave sin.79

The Epistle of James cited above discusses some of these criminal acts that profane the Name of God:

Listen, my beloved brothers. Did not God choose those who are poor in the world to be rich in faith and heirs of the kingdom that he promised to those who love him? But you dishonored the poor person. Are not the rich oppressing you? And do they themselves not haul you off to court? Is it not they who blaspheme the noble name that was invoked over you? ~ Jas 2:5-7

Indeed, doing such acts is blasphemous. Our Lord Jesus Christ, though speaking the Truth, was condemned and put to death for blaspheming.

As confirmed Catholics, WE are "...he who comes in the name of the Lord..." That is what the sacraments of initiation do: they make us fit to act in God's NAME, as his little angels to other people.  Baptism births us into God's life, Eucharist infuses us into the very substance of God in every cell of our body and crevice of our spirit, and Confirmation commisions us with the authority to do His will "...on earth as it is in Heaven..."