Thank you for the Biblical interpretation question, “Does Isaiah 66:15-18 say we have to keep the food and incense laws?”
As a Christian, my answer is a controversial one. For one’s consideration, my thinking at this point is that the Israelites will be offering sacrifices and obeying the Law in the Kingdom of God. Ezekiel 40–47 further clarifies what happens during the time period when God reigns over the whole earth.
Both Isaiah 66 and Ezekiel 40–47 relates to the Jewish people. According to Ezekiel, there will be a Messianic Temple where the Prince or Messiah rules over the whole earth. This Temple is not one that the returning Jews built from their exile from Babylon.
The text states that the Israelites will bring offerings to the Messianic Temple. Ezek. 44 says this, “‘I am to be the only inheritance the priests have. You are to give them no possession in Israel; I will be their possession. 29 They will eat the grain offerings, the sin offerings and the guilt offerings; and everything in Israel devoted to the LORD will belong to them. 30 The best of all the firstfruits and of all your special gifts will belong to the priests. You are to give them the first portion of your ground meal so that a blessing may rest on your household. 31 The priests must not eat anything, whether bird or animal, found dead or torn by wild animals” (A searchable online Bible in over 150 versions and 50 languages). There is the restoration of the priesthood and the sacrifices. The Prince himself will also offer sacrifices in the Temple which are provided by the Israelites.
Isa 66 says this, “18 And I, because of what they have planned and done, am about to come and gather the people of all nations and languages, and they will come and see my glory. 19 “I will set a sign among them, and I will send some of those who survive to the nations—to Tarshish, to the Libyans and Lydians (famous as archers), to Tubal and Greece, and to the distant islands that have not heard of my fame or seen my glory. They will proclaim my glory among the nations. 20 And they will bring all your people, from all the nations, to my holy mountain in Jerusalem as an offering to the LORD—on horses, in chariots and wagons, and on mules and camels,” says the LORD. “They will bring them, as the Israelites bring their grain offerings, to the temple of the Lord in ceremonially clean vessels. 21 And I will select some of them also to be priests and Levites,” says the LORD” (NIV).
It appears to me that the Israelites will be upholding/following the Law during the Kingdom Period. With the coming of the Prince or the Messiah, he will gather his people together to the Promised Land. It is during this time period that the offerings are inaugurated. The righteous individuals enter the Kingdom of God while the ungodly are excluded from the Kingdom of God. People will be born in the Kingdom Period.
Ezekiel 36 says this, “‘For I will take you out of the nations; I will gather you from all the countries and bring you back into your own land. 25 I will sprinkle clean water on you, and you will be clean; I will cleanse you from all your impurities and from all your idols. 26 I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give you a heart of flesh. 27 And I will put my Spirit in you and move you to follow my decrees and be careful to keep my laws. 28 Then you will live in the land I gave your ancestors; you will be my people, and I will be your God” (NIV).
The Israelites who return to the Promised Land will want to obey the commands of God. It will not be out of obligation but of thankfulness for redeeming them and bringing them back to the Promised Land. They will follow God’s decrees and keep his laws from their hearts in the Kingdom Period.
During this time period, are followers of Jesus obligated to obey the Law?
Does this contradict the Christian viewpoint? That is a very controversial question as many Christians advocate the abolishment of the Law. That is true, in my viewpoint, in the sense that it was never given as a means of salvation. The Law was not given to earn salvation. The Law was given to reflect a redeemed people who accepted the LORD God as their God. They were to be a unique people, a royal priesthood. The manner in which the people were to live was to reflect that privilege position before God. In other words, the Law was given for the Israelites to remain in fellowship with God and to serve him as his priest before the nations.
Christians do not obey the commands of Jesus or live the Christ-like life to earn salvation. They obey the commands of Christ because they are grateful for the gift of salvation by faith to them. They love him because he first loved them. Thus in the same manners, Jews obey the commands of God not for salvation but because God has provided the way of forgiveness for them through the sacrifices in the Old Testament.
SUMMARY: Israelites will obey the Law out of thankfulness of God’s redemption and blessings on them.
For more perspectives:
https://www.quora.com/Does-Isaiah-66-15-18-say-we-have-to-keep-the-food-and-incense-laws