Q. 110. What doth God forbid in the eighth commandment?
God forbids not only those thefts, and robberies, which are punishable by the magistrate; but He comprehends under the name of theft all wicked tricks and devices, whereby we design to appropriate to ourselves the goods which belong to our neighbour: whether it be by force, or under the appearance of right, as by unjust weights, ells, measures, fraudulent merchandise, false coins, usury, or by any other way forbidden by God; as also all covetousness, all abuse and waste of His gifts.
 1 Corinthians 6:10;  1 Corinthians 5:10;  Luke 3:14; 1 Thessalonians 4:6;  Proverbs 11:1;  Ezekiel 45:9–11; Deuteronomy 25:13;  Psalm 15:5; Luke 6:35;  1 Corinthians 6:10.
Q. 111. But what doth God require in this commandment?
That I promote the advantage of my neighbour in every instance I can or may; and deal with him as I desire to be dealt with by others: further also that I faithfully labour, so that I may be able to relieve the needy.
 Matthew 7:12;  Proverbs 5:16; Ephesians 4:28.
The Eighth Commandment, “Thou shalt not steal,” has to do with ownership of property. God has assigned to everyone a portion of the things of this world to enjoy and to manage. This command teaches us to respect and protect this apportionment of God, as well as to procure anything that we do not at present have only by biblically lawful means. This looks simple enough, but in practice, even professing Christians violate the Eighth Commandment without so much of a flutter of the conscience.
For example, it is a breaking of the Eighth Commandment to use pirated software, or to make copies of books against the expressed copyright notice. Many do not think that these actions violate God’s laws, simply because they do not involve stealing something tangible from another. But the fact is that violation of copyrights involves lost of incomes or royalties which rightly belong to the copyright holders. Similarly, overcharging for goods or service, or unfair bargaining in the case of purchase, is also a violation of the Eighth Commandment (Prov 20:10; 11:1; 20:14), because it involves demanding more than what you deserve lawfully or a refusal to pay the amount that the providers of the goods or services actually deserve.
What about the use of time? Failure to work the number of hours required in our contract is surely a breaking of the Eighth Commandment too, since we are being paid for what we did not do. What about late coming in appointments which may not involve cash value, such as meeting with friends or attendance at the means of grace? I believe these are also violations of the Eighth Commandment because when an appointment is made, you actually promise to give a portion of your time beginning at a particular time. Failure to turn up at the stated time is technically stealing that portion of time, which you have agreed to give. Singaporeans must especially be mindful of this failure, for even Christians are often habitually late without feeling any shame at all.
Moreover, in so far as the Eighth Commandment is about the management of the temporal wealth, we note that it also requires us to secure a regular income so that we may contribute to the needy (Eph 4:28); as well as to manage our wealth wisely so that we do not squander away what God has graciously assigned to us.
Heidelberg Catechism >