All Christians rightly believe that God wrote Ten Commandments (or words) on the tablets he gave to Moses on Mount Sinai.
This is confirmed by three Old Testament texts which clearly designate the correct number:
Exodus 34:28: “So he was there with the Lord for forty days and forty nights; he did not eat bread or drink water. And He wrote on the tablets the words of the covenant, the Ten Commandments [lit. words].”
Deuteronomy 4:13: “So He declared to you His covenant which He commanded you to perform, that is, the Ten Commandments [lit. words]; and He wrote them on two tablets of stone.”
Deuteronomy 10:4: “Then He wrote on the tablets, like the first writing, the Ten Commandments [lit. words] which the Lord had spoken to you on the mountain from the midst of the fire on the day of the assembly; and the Lord gave them to me.”
While all Christians agree on the number of commandments, however, we do not agree on the numbering of the Ten Commandments. The major disagreement that divides Reformed Protestants from Roman Catholics and Lutherans is over the distinctiveness of the second commandment.
For example, in Luther’s Small Catechism, he writes that the first commandment is, “You shall have no other gods.” So far, so good. But then he writes that the second commandment is, “You shall not make wrongful use of the name of the Lord your God.” So, according to Lutherans and Roman Catholics, Exodus 20:4-6 should be subsumed under the first commandment.
But if those verses are subsumed under the first commandment, how do Roman Catholics and Lutherans arrive at Ten Commandments? Here’s how: In Luther’s Small Catechism, he writes that the ninth commandment is, “You shall not covet your neighbor’s house.” And then he writes that the tenth commandment is, “You shall not covet your neighbor’s wife, or male or female servant, or ox, or donkey, or anything that belongs to your neighbor.” Lutherans and Roman Catholics, therefore, split up what the Reformed consider to be the tenth commandment into two commandments (both dealing with coveting). Roman Catholics believe that the ninth commandment deals with carnal concupiscence and the tenth with coveting a neighbor's goods.
The question is, who counts the commandments correctly?
Here are four basic arguments Reformed people should insist on in this disagreement:
1. The first argument against a Lutheran or Roman Catholic counting of the commandments is that it is arbitrary to break up the commandment to not covet into two distinct commandments forbidding the same thing.
One of the exegetical reasons we know this is the case is because of the distinctive ordering of the tenth commandment in Exodus 20 as compared to Deuteronomy 5. In Exodus 20, the first thing we are forbidden to covet is our neighbor’s house (Exodus 20:17). Luther says that this is the ninth commandment. However, in Deuteronomy the first thing we are forbidden to covet is our neighbor’s wife (Deuteronomy 5:21). What exegetical reasons prevent us from saying that the ninth commandment is actually the forbidding of coveting our neighbor’s wife, rather than his house?
Lutherans and Catholics thus make an arbitrary distinction that does not properly take into account the ordering of the words in both places where the Ten Commandments are recorded, a variance that would indicate a single command not to covet (i.e. the forbidding of covetousness).
2. The second argument for the correctness of the Reformed Protestant counting of the commandments is found in those passages where the second commandment is explicitly violated, but not the first.
In other words, the Bible speaks of times when the worship of YHWH was perverted by imagery, which would indicate that verses 4-6 are a second, distinctive commandment (not just who is to be worshipped but how God is to be worshipped). Exodus 32:4-5 speaks of the famous incident with Israel at the foot of Mount Sinai with the golden calf. This is what it says, “Aaron took the gold from them, fashioned it with an engraving tool, and made it into an image of a calf. Then they said, “Israel, this is your god who brought you up from the land of Egypt!” When Aaron saw this, he built an altar in front of it and made an announcement: ‘There will be a festival to YHWH tomorrow.”
Note that the festival was going to be for YHWH, the covenant God. In other words, the first commandment was not being violated, but the second commandment was.
This is made even clearer from a story from 2 Kings 10:18-31. Space precludes the inclusion of all the verses, but in verses 28-31 it says that Jehu faithfully, “eradicated Baal from Israel. However, as for the sins of Jeroboam the son of Nebat, into which he misled Israel, from these Jehu did not desist, including the golden calves that were at Bethel and at Dan. Yet the Lord said to Jehu, “Because you have done well in performing what is right in My eyes, and have done to the house of Ahab in accordance with everything that was in My heart, your sons to the fourth generation shall sit on the throne of Israel.” But Jehu was not careful to walk in the Law of the Lord, the God of Israel, with all his heart; he did not desist from the sins of Jeroboam, into which he misled Israel.”
Was it sufficient for Jehu to expel the worship of Baal from Israel so that only YHWH was worshipped? No. That Jehu restored the worship of YHWH to Israel was good, but not enough. The problem was that he didn’t turn from the perverted worship (i.e. the breaking of the second commandment) that Jeroboam had instituted earlier in Israel’s history, worship God had not authorized.
3. A third argument comes from Acts 17 where Paul spoke to the philosophers at Mars Hill. In his defense of Christian doctrine, Paul did not simply say, “You are worshipping false gods.” He also indicated that the way they were worshipping was faulty because they thought that the divine nature of God could be imaged, a clear violation of Exodus 20:4-6. If all the pagans in Athens turned and worshipped only the true God via the altar they had made, would Paul have been pleased? Of course not! And why not? Because not only were they worshipping false gods, but they were worshipping false gods falsely. Once again, we find that Exodus 20:4-6 is a distinctive commandment.
4. The final argument against the Lutheran and Roman Catholic numbering of the commandments is found by looking at Romans 7:7-13. The question here is a simple one. Did Paul consider the forbidding of coveting to be a single command? Look at the answer for yourself, "For I would not have known covetousness unless the law had said,'You shall not covet.' But sin, taking opportunity by the commandment, produced in me all manner of evil desire. For apart from the law sin was dead. I was alive once without the law, but when the commandment came, sin revived and I died. And the commandment, which was to bring life, I found to bring death. For sin, taking occasion by the commandment, deceived me, and by it killed me. Therefore the law is holy, and the commandment holy and just and good. Has then what is good become death to me? Certainly not! But sin, that it might appear sin, was producing death in me through what is good, so that sin through the commandment might become exceedingly sinful."
Not only is covetousness the category covered by the tenth commandment, but five times Paul specifies commandment with the article the to indicate a single commandment. We do not, therefore, need to arbitrarily break up the last commandment into two commandments forbidding the same thing. We are on firm exegetical ground to count Exodus 20:4-6 as its own commandment.