If we, as Christians, no longer follow the laws of the Old Testament, does that also apply to the Ten Commandments?
People today tend to look at the Ten Commandments as an entity separate from the Mosaical Law. Yet, these ten commandments were the prelude to the body of laws Moses brought down from Mount Sinai. If you read through the laws given, from Exodus 20:22-23:33, you will find that these laws are expansions on the Ten Commandments -- they expressed in detail what God meant by each of the commandments, as well as how to punish violations of the commandments. For example, did you realize that violation of any of the Ten Commandments carried the potential penalty of death? I sometimes wonder why people are eager to retain the Ten Commandments, but they do not want to keep God's consequences for violating those commandments.
The Ten Commandments were unique to Israel
When Moses recited the laws given at Mount Sinai, he said, "Hear, O Israel, the statutes and judgments which I speak in your hearing today, that you may learn them and be careful to observe them. The LORD our God made a covenant with us in Horeb. The LORD did not make this covenant with our fathers, but with us, those who are here today, all of us who are alive" (Deuteronomy 5:1-3). Immediately following this statement are the Ten Commandments and the rest of God's laws for Israel. Notice that Moses said that these laws, including the Ten Commandments, did not exist prior to Israel's arrival at Mount Sinai and that the laws were given to Israel. Now, in case you are among those who try to play word games and object by say "Moses was talking about the covenant, not the Ten Commandments;" turn back to Deuteronomy 4:13, "So He declared to you His covenant which He commanded you to perform, the Ten Commandments; and He wrote them on two tablets of stone." The Ten Commandments is the summary of the covenant God made with Israel.
Now did this mean that things like murdering, lying, and idol worshipping were not sins prior to Israel receiving the Law? Obviously not! Cain was guilty of murder long before Moses lived (Genesis 4). Abraham sinned when he lied about his relationship with Sarah. In fact, Paul notes, "Nevertheless death reigned from Adam to Moses, even over those who had not sinned according to the likeness of the transgression of Adam, who is a type of Him who was to come" (Romans 5:14). Death reigns through sin and death reigned from the time of Adam all the way to the time of Moses. The implication is that laws existed from Adam to Moses that man had violated. What was unique was this particular embodiment of laws. Only Israel received this particular set.
Moses also said, "For what great nation is there that has God so near to it, as the LORD our God is to us, for whatever reason we may call upon Him? And what great nation is there that has such statutes and righteous judgments as are in all this law which I set before you this day?" (Deuteronomy 4:7-8). The whole law, including the Ten Commandments, was unique to Israel. No other nation had such a law. Contrast this to the Law of Christ. It is to be taught to everyone. "Go into all the world and preach the gospel to every creature" (Mark 16:15). It applies to both Jew and Gentile. "For I am not ashamed of the gospel of Christ, for it is the power of God to salvation for everyone who believes, for the Jew first and also for the Greek" (Romans 1:16).
The Ten Commandments were not a complete law by themselves
For example, the Israelites were required to circumcise their male children. "And the uncircumcised male child, who is not circumcised in the flesh of his foreskin, that person shall be cut off from his people; he has broken My covenant" (Genesis 17:14). Yet, circumcision is not mentioned in the Ten Commandments. Israel had to make sacrifices, have a priesthood, and observe special feast days; yet, none of these appear in the Ten Commandments.
While the Ten Commandments were a summary of the Law of Moses, they were not the entire law nor were they a complete summary. To claim such would be similar to claiming that the prologue of the Constitution complete describes the entire document.
Interestingly, when Jesus was asked to summarize the law (Matthew 22:37-40), he did not turn to any of the Ten Commandments; instead, he quoted from Deuteronomy 6:5 and Leviticus 19:18. Neither of these passages is a part of the Ten Commandments.
One of the Ten Commandments was not carried over into the Law of Christ
You can find nine of the ten commandments in the New Testament. They are not neatly listed as they were in Moses' Law, but the rules still exist. The only one not found in the New Testament is the commandment concerning the Sabbath day. Such shouldn't be surprising. Of the Ten Commandments, the command concerning the Sabbath day was uniquely significant to the people of Israel. "And remember that you were a slave in the land of Egypt, and the LORD your God brought you out from there by a mighty hand and by an outstretched arm; therefore the LORD your God commanded you to keep the Sabbath day" (Deuteronomy 5:15). By the way, this quote is taken from the recitation of the Ten Commandments. While Israel experienced slavery in Egypt and a day of rest was a fitting memorial of their past suffering, such cannot be said for the rest of the nations.
Paul stated that the Gentiles benefited from Jesus' death. "And you, being dead in your trespasses and the uncircumcision of your flesh, He has made alive together with Him, having forgiven you all trespasses, having wiped out the handwriting of requirements that was against us, which was contrary to us. And He has taken it out of the way, having nailed it to the cross" (Colossians 2:13-14). It was the Ten Commandments which were written by the hand of God on tablets of stone. In another letter, Paul wrote, "clearly you are an epistle of Christ, ministered by us, written not with ink but by the Spirit of the living God, not on tablets of stone but on tablets of flesh, that is, of the heart. ... who also made us sufficient as ministers of the new covenant, not of the letter but of the Spirit; for the letter kills, but the Spirit gives life. But if the ministry of death, written and engraved on stones, was glorious, so that the children of Israel could not look steadily at the face of Moses because of the glory of his countenance, which glory was passing away, how will the ministry of the Spirit not be more glorious?" (II Corinthians 3:3, 6-8). Hence, if Christians who grew up as Jews wanted to observe festivals from the Old Law, that was fine for them. However, they could not apply their desires to their Gentile brethren. Speaking to the Gentile Christians, Paul said "So let no one judge you in food or in drink, or regarding a festival or a new moon or sabbaths, which are a shadow of things to come, but the substance is of Christ" (Colossians 2:16-17). Gentiles had no reason to keep the old laws of food, drink, festivals, or sabbaths; such were observed by Jews. The provisions of the Old Law were merely a shadow of the reality of Christ's law and as such were nailed to the Cross. But notice that one of the laws named is the observance of the Sabbath. Not all of the Ten Commandments were carried over into the law of Christ.