There is the question of which commandments we are to obey in 1 John 5:3 and in 2 John 1:6, as the result of loving the Lord our God with all of our heart, soul, mind, and strength.
In the whole of the Torah, these verses best describe what it means to love God with all of our heart, mind, soul, and strength:
Deuteronomy 10:12-13 “And now, Israel, what does the Lord your God require of you, but to fear the Lord your God, to walk in all his ways, to love him, to serve the Lord your God with all your heart and with all your soul, 13 and to keep the commandments and statutes of the Lord, which I am commanding you today for your good?
Do we obey all of the commandments in the Old Testament? Matthew 5:17-20, Hebrews 8:10, Hebrews 10:16, Jeremiah 31:33, Romans 8:4-7 would seem to tell us so.
We will be called great in the kingdom if we obey and teach the least of these God's commandments. In context (in Matthew 5:17-20) Jesus is talking about the Old Testament law.
Agreed.
But concerning this, it seems that Jesus Himself taught that the Old Testament commandments concerning food laws and the sabbath are now invalid. For He Himself broke the sabbath according to John's testimony (John 5:18); and He also proclaimed on more than one occasion that all foods are now clean (Mark 7:14-19, Luke 11:41, Romans 14:14).
According to Deuteronomy 4:2, it is a sin to add to or subtract from what the Father commanded, and Jesus was sinless, so he didn't do that. Likewise, in Deuteronomy 13:4-5, the way that God instructed His people to determine whether someone was a false prophet who was not speaking for him was if they taught against obeying what He commanded, so if you think that Jesus did that, then you should think that he was a false prophet. Sadly, Christians saying that Jesus taught against OT commandments is one of the biggest reasons why Jews have rejected him as their Messiah.
It is contradictory to hold both the positions that Jesus was correct about it being lawful to heal on the Sabbath and the position that the John 5:18 that the Pharisees were correctly in thinking that Jesus broke the Sabbath by healing on it. That verse states the reason that the Pharisees has for wanting to kill him, but that reason was incorrectly because Jesus hadn't actually broken the Sabbath.
In Mark 7:1-5, Jesus was being asked why his disciples broke the traditions of the elders taught taught that they could become common by eating with common hands. In Mark 7:6-13, Jesus criticized the Pharisees as being hypocrites for setting aside the commands of God in order to establish their own traditions. So Mark 7:14-19 should be interpreted as Jesus continuing to speak against being made common by what we eat instead of even more hypocritically turning around and doing what he just finished criticizing the Pharisees for doing.
In Romans 14, the topic of the chapter is stated in the first verse, namely it is in regard to how to handle disputable matters of opinion, not in regard to whether followers of God should follow God, so nothing in that chapter should be interpreted as speaking against following His commands.
Yet the law is a schoolmaster to lead men to Christ (Galatians 3:24-25); it shows men their sin (Romans 3:20) and brings them to the place of being converted (Psalms 19:7). I don't think that this is talking about the law as it is now that it has been changed for the believer (Hebrews 7:12).
Having no more need for a tutor is not at all the same as having no more need to live by what they taught you. Someone who disregarded everything their tutor taught them after they left would be completely missing the whole point of a tutor. Now that Christ has come we have a superior teacher, but the subject matter is still how to walk in God's ways in obedience to His Law in accordance with that he taught by word and by example.
The existence of sin requires there to be a standard of what is and is not sin, and this standard is God's eternal Law. Sin was in the world before the Law was given, so the things that are sin are not specific to any particular covenant. For example, it will always be righteous to help the poor and sinful to commit murder no matter how many covenants God makes, so any instructions that God has ever given in that regard will always be valid no matter which covenant we are under. If you believe that God's Law was given to reveal what sin is and that you should refrain from what God has revealed to be sin, then you should obey it.
In Hebrews 7:12, it is not speaking about a change in God's eternal righteousness with things that are righteous becoming sinful and vice versa, such as it now being righteous to commit murder, but rather the context is speaking about a transition of the priesthood, which would also require a transition of the law to go along with it in regard to its administration.
The law has only been changed in that it is no longer given to us as a set of do's and don'ts, but as a list of virtues to be exemplified and vices to be avoided (Galatians 5:16-24). We are told not to walk according to the flesh and that we will reap what we sow, even as believers (Galatians 6:7-8).
There are many verses that describe the Mosaic Law as being instructions for how to walk in God's ways, such as Deuteronomy 10:12-13, Isaiah 2:2-3, Joshua 22:5, Psalms 103:7, and many others, so the Law has always been about teaching us how to express God's character traits, such as holiness, righteousness, goodness, justice, mercy, faithfulness, and other fruits of the Spirit. Walking according to the flesh is always walking in disobedience to God's Law, such as the works of the flesh that are against the Spirit that are listed in Galatians 5:19-22.
And also, the Old Testament sacrifices are no longer needed, because Christ dying on the Cross is the fulfillment of them.
"To fulfill the Law" means "to cause God's will (as made known in the Law) to be obeyed as it should be" (NAS Greek Lexicon pleroo 2c3). After Jesus said he came to fulfill the Law in Matthew 5, this is precisely what he then proceeded to do six times throughout the rest of the chapter by teaching how to correctly understand and obey it. In Galatians 5:14, loving your neighbor fulfills the entire law, so it refers to obeying the Law as it should be obeyed, and refers to something countless people have done, not to something unique to Christ. Likewise, Galatians 6:2 says that bearing one another's burdens fulfills the Law of Christ, so you should interpret it in the same way as fulfilling the Law and the Prophets, namely obeying it as it should be, not as doing away with it. In Romans 15:18-19, it says that Paul fulfilled the Gospel, which again referred to causing Gentiles to become fully obedient to it in word and in deed, not to doing away with it.
So then, concerning food laws and sabbath days, it seems that if I am going to be great in the kingdom, I should obey and teach them (Matthew 5:17-20); however it also seems that Jesus Himself taught that the sabbath is not all-important, and that neither are the food laws.
Jesus never taught that the Sabbath was unimportant, but rather he continued to keep it throughout his ministry, and and his followers we are told to follow his example (1 Peter 2:21-22). You are suggesting that by his own words Jesus will be least in the Kingdom.
God is wanting to bring back His Jewish people into the fold of those accepted by Him through faith in the Messiah. In 1 Corinthians 8 and Romans 14, we are told to be sensitive to the consciences of our weaker brothers and sisters (those who feel that the food laws define what is clean and unclean; or those who hold the sabbath day above other days). Perhaps even to the extent of observing these laws ourselves, since at any moment we might come into contact with a weaker brother or sister, who may be stumbled by our liberty, their conscience being emboldened to eat what they do not in reality have liberty to eat. We ought to bear the infirmities of the weak and not to please ourselves, even if we ourselves are stronger and feel that we have the liberty to eat what is unclean or to work on Saturday. Jesus did say that it is lawful to do well, what is good and right, on the sabbath days. He redefined the sabbath for us; He is the Lord of the sabbath; I am not certain that He abolished it completely. It is an excellent principle to follow that we should set aside time to rest and spend time with the Lord between Him and us alone. And food laws are now reduced to being an indicating factor of whether or not we have the love of God in our hearts towards a weaker brother, since in 1 Timothy 4:1-6 it becomes clear that every creature of God is good and nothing to be refused if it be received with thanksgiving; for it is sanctified by the word of God and prayer. So as Gentile believers we have the right to eat what our culture tells us is good; while if we know that we even might be in the presence of a weaker (Jewish) brother or sister we ought to be sensitive to their consciences and refrain from eating what we might otherwise have liberty to eat.
Paul continued to keep the Sabbath throughout Acts, so he was not referring himself as being weak. It is not weak to think that we should obey what God has commanded, but quite the opposite. The liberty that we have in Christ is the freedom from sin, not the freedom to do the things that God revealed in His Law to be sin. Jesus did not redefine the Sabbath, but rather he taught how to correctly keep it as it was originally intended. In 1 Timothy 4:1-6, Paul described what he was speaking about as the doctrines of demons, which should be a major clue that he was not speaking about the holy, righteous, and good commands of God.
And Jesus healed on the sabbath, even though it stumbled the scribes and Pharisees who were looking onward. However He was redefining the sabbath as the One who made it; because the scribes and Pharisees had taken it too far and had made an idol out of keeping strict laws concerning it. Paul's exhortation in Romans 14 concerning the sabbath is let every man be fully convinced in his own mind as to whether he holds one day above another or whether he holds every day alike. And the weaker brother is not to judge the stronger brother; and the stronger brother is not to hold the weaker brother in contempt.
If Jesus could redefine what counted as sin, then the fact that he was sinless would have no significance. The Sabbath isn't even mentioned in Romans 14, nor is it even related to the topic he was speaking about. In Galatians 6:1-4, we are instructed to gently restore those who are caught in sin, so Paul was not suggesting that we are free to sin all we like just as long as we are convinced in our own minds that it is ok.
