How is God's name profanely abused in hearing or reading his word ?

The third use of the law – the law as a guide for Christian gratitude to God for his saving grace is one of those important strands of Reformed theology. Take this strand out of Reformed theology and you end up with legalism, antinomianism, and a host of other tragic errors. Christians should know the law of God, most definitely. But they should also know the uses of it: to show them their sin, driving them to Christ, and to show them how to thank Christ in faith-filled obedience. The Puritans and the old divines taught this concept. Today it is almost lost in Christian life and the pursuit of holiness. They understood that a right understanding, (empowered by the grace of God) of the Moral Law of God aids the believer in his sanctification.

In the book Marrow of Modern Divinity the writer discusses the Moral law of God and its use in the Christian life. Here is a conversation between Neophytus, a young Christian and Evangelista, a minister of the gospel. This small snippet of their conversation was convicting and edifying. In this part of the dialogue Evangelista is giving the negative aspects of the 3rd commandment. This is a small part of that greater discussion.

Neo. And how is God's name profanely abused in hearing or reading his word?

Evan. God's name is hereby abused, when we hear it or read it, and do not understand it.
(Acts 8: 30) ; and when we hear it only with the outward ears of our bodies, and not also with the inward ears of our heart and soul; and this we do when we read it or hear it with our hearts full of wandering thoughts, (Ezek. 33: 30) ; and we read it, or hear it with dull, drowsy, and sleepy spirits ; and when in hearing of it we rather conceive it to be the word of a mortal man that delivers it, than the word of the great God of heaven and earth, (1 Thess.2:13) and when we do not with our hearts believe every part and portion of that word which we read or hear, (Heb. 4: 2) ; and when we do not humbly and heartily subject ourselves to what we read or hear, (2 Kings 22:19 ; Isa. 62:2)

1689 London Baptist Confession of Faith
on the "third use of the Law"

Paragraph 5. The moral law does for ever bind all, as well justified persons as others, to the obedience thereof,10 and that not only in regard of the matter contained in it, but also in respect of the authority of God the Creator, who gave it;11 neither does Christ in the Gospel any way dissolve, but much strengthen this obligation.12

10 Rom. 13:8-10; James 2:8,10-12
11 James 2:10,11
12 Matt. 5:17-19; Rom. 3:31

Paragraph 6. Although true believers are not under the law as a covenant of works, to be thereby justified or condemned,13 yet it is of great use to them as well as to others, in that as a rule of life, informing them of the will of God and their duty, it directs and binds them to walk accordingly; discovering also the sinful pollutions of their natures, hearts, and lives, so as examining themselves thereby, they may come to further conviction of, humiliation for, and hatred against, sin;14 together with a clearer sight of the need they have of Christ and the
perfection of his obedience; it is likewise of use to the regenerate to restrain their corruptions, in that it forbids sin; and the threatenings of it serve to show what even their sins deserve, and what afflictions in this life they may expect for them, although freed from the curse and unallayed rigour thereof. The promises of it likewise show them God's approbation of obedience, and what blessings they may expect upon the performance thereof, though not as due to them by the law as a covenant of works; so as man's doing good and refraining from evil, because the law encourages to the one and deters from the other, is no evidence of his being under the law and not under grace.15

13 Rom. 6:14; Gal. 2:16; Rom. 8:1, 10:4
14 Rom. 3:20, 7:7, etc.
15 Rom. 6:12-14; 1 Pet. 3:8-13

Paragraph 7. Neither are the aforementioned uses of the law contrary to the grace of the Gospel, but do sweetly comply with it,16 the Spirit of Christ subduing and enabling the will of man to do that freely and cheerfully which the will of God, revealed in the law, requires to be done17

16 Gal. 3:21
17 Ezek. 36:27