This is in reply to a young brother in the Lord who wants to be true to the what the Lord Yeshua has accomplished on the cross, and to the Word of God as given in the Law of Moses:
The very fact the YHVH God has established ‘everlasting ordinances’ with/in Israel is a Scriptural answer to those who say that God has no more plan for Israel as a nation, or for this promised land as an inheritance. Also, these everlasting ordinances are specifically given to Israel, and so the New Testament does not impose the ones you refer to upon the Church — redeemed, born-again, men and women from among Israel and from any other nation.
But the believer is supposed to uphold the truth of God’s word — including that there is an everlasting promise to be fulfilled, even if that promise is an ordinance. Every jot and tittle of the Law and the Prophets will be fulfilled. The Millennial Kingdom is what God has promised that will bring to fulfillment every promise that is everlasting in this creation, in these heavens and Earth, until the end of time. If you look at the last nine chapters of Ezekiel (40-48), which describe what can only be properly understood, I think, as looking ahead to the 1000-year kingdom to come after Jesus returns, you will see all those ordinances that you refer to. We can certainly observe some of the holidays today as believers, especially here in Israel, but for those in Christ, we enter through faith into a new relationship with God that no longer requires keeping religiously types and shadows, since we have the substance, who is Messiah.
Yom Ha-Kippurim (Day of Atonements) does not specifically mention a fast, but to “afflict your souls”. An afflicted soul will not want to eat, or feel like eating, but not eating does not afflict our souls. When Israel sees Him whom they have pierced . . .(Zech 12), the nation will afflict their souls, and have their full atonement, which will last forever on the basis of the sacrifice which YHVH required that they accept if they want to be accepted by Him (Lev 23:29-32). For us who already believe, even if we are Israeli Jews, we do not need any more to fast or offer another sacrifice for our sins, since we have already accepted God’s sacrifice of Yeshua, and, hopefully, each of has afflicted our souls when we recognized that He died for me and for my sins, just as the full remnant that will be all Israel as a nation — each one individually and all together corporately– will do “in that day”. (As we grow in our Messiah-like character, we will be repenting of sin, which will cause a continuing measure of soul affliction as we humble ourselves by confessing our sins and accepting forgiveness, all this leading to further thanksgiving and praise to God.)
“Olam” has different meanings. It can mean ‘world’, ‘forever’, ‘everlasting’, ‘age’ (as in ‘end of the age’). For an individual person, his ‘olam‘ can be said to end when he dies. (We who are born-again have died with Messiah, been baptized in water into His death, and risen with Him through faith, baptized with the Holy Spirit into His life, to forevermore live unto God.) Yeshua received promises that were dependent upon His being raised from the dead in order to have them, so olam for Him personally is forever, even unto the ages to come (Eph 1:21, as one example). And this is true for all who are IN Messiah. When God promised the fathers the Land of Canaan as an everlasting possession; or to Aaron an everlasting priesthood (carried on through his son Eleazar, then God’s covenant with Phineas, on through Zadok), it is clear that God is going to do what He says, even though it seems to be “taking forever”. (Born-again believers are not Levitical priests, though, but of another and transcendant priesthood with Yeshua, after the order of Melchizedek. This necessarily, according to the Letter to the Hebrews, brings a change of the Law for us, and is why not all of the ordinances given to Israel still apply to us, even though some of them are “everlasting”, and even if some of us are Jews.) The Millennial Kingdom will see these everlasting ordinances to and through Israel restored and fulfilled, through to the end of time. (There is no ‘time’ in the eternal new heavens and new earth.) Everlasting life is eternal, without end; shame and everlasting contempt for those who will be in hell uses the same word for everlasting (olam) in Dan 12:2, meaning everlasting existence , without end: each truth applies according to their respective resurrections.
So we who believe establish the Law by faith (Rom 3:31), and the Law is a tutor to bring sinners to repentance and faith in Messiah: God is faithful and will fulfill all things in righteousness for His holy name’s sake, for He has spoken!