Christ said a new way of doing God's will that is to replace the old way of doing things, the way the Law was being done at that time.
"...a time is coming when you will worship the Father neither on this mountain nor in Jerusalem. ... Yet a time is coming and has now come when the true worshipers will worship the Father in the Spirit and in truth, for they are the kind of worshipers the Father seeks.
24 God is spirit, and his worshipers must worship in the Spirit and in truth.”
So, all the old way of
outward forms, performing rituals and sacrifices and the outward-only versions of following the Law -- all to be replaced with the true thing instead, the real spirit of the Law. The Law fulfilled. Done right.
"For I desire mercy, not sacrifice, and acknowledgment of God rather than burnt offerings." -- Hosea 6:6, Matthew 9:13
That is, the typical way the Law was being followed was going to be changed, to increase an actual following of the real essence of the Law.
The new way to be followed would be "in spirit and in truth", and the old way was not good enough.
The Pharisee way of following the Law, lacking both spirit and lacking in-truth, would be corrected and replaced with the true version, having the spirit correct.
This is how the law "
is" now --
"So in everything, do to others as you would have them to do you, for this is the law and the prophets".
You can call it the "how to" rule for doing "Love your neighbor as yourself", and this rule can even help us with relating to God the right way. We know we are to Love God with all of our hearts, and all of our minds, and all of our souls, and all of our might. I.e. -- we are to love Him as we most profoundly want to be loved.
So when Christ says all the law hangs on the two greatest commandments, I think it's a full statement of all the law now. It's not a halfway-there. Not a reduction. Instead, this is the true essence of the all. It's complete.
Well, we have to clarify a few things:
1) The Law as it was done at the time of Jesus' first coming had burdensome Jewish traditions added to it, which should not happen because we shouldn't add commands to/remove commands from the Law (Deuteronomy 4:2, 12:32, 28:14, and 13:1-5).
2) Truth is defined as the Law (Psalm 119:142). So, when Jesus says that God's worshipers will worship Him in both Spirit and Truth, it means, in my opinion, that we will walk in both the word of the Law (the commands in Genesis through Deuteronomy) and the correct application of it (Spirit). But Jesus did not give a new Law or change the Law. If He did, then He wouldn't be sinless since He would be breaking Deuteronomy 4:2, 12:32, 28:14, and 13:1-5.
3) Hosea 6:6 is said in the context that Israel was going through the motions of sacrifices and not repenting and walking in the Law. Notice how it says "I desire...acknowledgment of God rather than burnt offerings". How do we acknowledge God? We acknowledge that He is our Master by serving Him. How do we serve Him? By obeying Him. How do we obey Him? By following His commands. What are His commands? The Law. See Proverbs 3:1-6 and Deuteronomy 28:14 below:
Proverbs 3:1-6:
1 My son, do not forget my law,
But let your heart keep my commands;
2 For length of days and long life
And peace they will add to you.
3
Let not mercy and truth (the Law per Psalm 119:142) forsake you;
Bind them around your neck,
Write them on the tablet of your heart,
4
And so find favor and high esteem
In the sight of God and man.
5 Trust in the Lord with all your heart,
And lean not on your own understanding;
6
In all your ways acknowledge Him (the context of is remembering to do the Law, so acknowledging God is walking in His Law),
And He shall direct your paths.
Deuteronomy 28:14:
So you shall not turn aside from any of the words which I command you this day,
to the right or the left,
to go after other gods to serve them (who you obey is who you serve. If you obey the Law, you serve God. If you obey commands other than the Law, then you serve other gods).
So when Christ says all the law hangs on the two greatest commandments, I think it's a full statement of all the law now. It's not a halfway-there. Not a reduction. Instead, this is the true essence of the all. It's complete.
Jesus could not have completed the Law. It's already perfect/complete. Consider Proverbs 19:7: "The law of the LORD is perfect". The Hebrew word that translates to "perfect" here is "tamiym
". It can also mean "complete, entire, whole, sound". So, per Psalm 19:7 the Law is complete. This is also the reason you have Deuteronomy 4:2, 12:32, 28:14, and 13:1-5 saying not to change/add to/remove from/alter the Law....because it is complete, perfect, entire, sound, "tamiym" already. Here is the Blue Letter Bible link for "tamiym" if you want to see the usage and definition for yourself:
Genesis 1:1 (NKJV)
Last thing I'll touch on: to my knowledge, the Bible says the sacrificial system will return in the future. I understand that may be a shocker, but read Ezekiel 40-48. To my knowledge, the temple that is described there has not been built yet.
Some noteworthy points about the Ezekiel 40-48 temple is that 1) the glory of God fills this temple (Ezekiel 44:4) (it is His dwelling place), 2) those who are uncircumcised in flesh or heart (regardless of whether they are a child of Israel or a foreigner) will not enter the temple (Ezekiel 44:9) (but of course, you can become circumcised in both heart and flesh and then enter the temple), 3) the Levitical priesthood will return (Ezekiel 44:10-31), 4) Passover and the Festival of Unleavened Bread is celebrated - not Easter (Ezekiel 45:21), 5) and sacrifices/offerings will be done once again (Ezekiel 44:27-29, 45:17, 42:13-14, 42:22).
Remember that almost all of these verses I've quoted are written as God's direct quotes to Ezekiel. These is literally God saying these things to Ezekiel.
Please don't think that I'm saying that Jesus was not your ultimate sacrifice by which you are saved. That's not what I'm saying by quoting Ezekiel 40-48. You are saved by His sacrifice. In my opinion, if our sin is wiped away/forgiven, then we won't have to do sin offerings - but the nations will. Instead, we will be allowed to make thanksgiving/peace offerings to God (Leviticus 3).
I hope this helps
!