It's another way of saying they are part of each other. Paul expressed this reality to the Romans concerning God's grace that gives us faith.
Romans 3:31 Do we then make void the law through faith? God forbid : yea, we establish the law.
Galatians 2:20-21
20 I am crucified with Christ: nevertheless I live ; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me.
21 I do not frustrate the grace of God: for if righteousness come by the law, then Christ is dead in vain.
Put it together, if we don't acknowledge the law as righteous and principles to adhere to, then we are sinning because we are not living by every word that proceeds out of the mouth of God. Jesus' words cannot be rejected as He quoted the law to our adversary.
Deuteronomy 8:3 And he humbled thee, and suffered thee to hunger , and fed thee with manna, which thou knewest not, neither did thy fathers know ; that he might make thee know that man doth not live by bread only, but by every word that proceedeth out of the mouth of the LORD doth man live .
What then? shall we sin , because we are not under the law, but under grace? God forbid . (Romans 6:15)
The physical temple and Levitical priesthood has passed. Jesus fulfilled that. Now if we love God and our neighbor we will adhere to the law that tells us how to do just that with detailed principles. The law was given because of transgression. That's graceful in my opinion.
Check it out, because true believers do this through faith, not by trying to be justified without faith.
Leviticus 19:15-18
15 Ye shall do no unrighteousness in judgment: thou shalt not respect the person of the poor, nor honour the person of the mighty: but in righteousness shalt thou judge thy neighbour.
16 Thou shalt not go up and down as a talebearer among thy people: neither shalt thou stand against the blood of thy neighbour: I am the LORD.
17 Thou shalt not hate thy brother in thine heart: thou shalt in any wise rebuke thy neighbour, and not suffer sin upon him.
18 Thou shalt not avenge , nor bear any grudge against the children of thy people, but thou shalt love thy neighbour as thyself: I am the LORD.
Deuteronomy 6:1-6
1 Now these are the commandments, the statutes, and the judgments, which the LORD your God commanded to teach you, that ye might do them in the land whither ye go to possess it:
2 That thou mightest fear the LORD thy God, to keep all his statutes and his commandments, which I command thee, thou, and thy son, and thy son's son, all the days of thy life; and that thy days may be prolonged .
3 Hear therefore, O Israel, and observe to do it; that it may be well with thee, and that ye may increase mightily, as the LORD God of thy fathers hath promised thee, in the land that floweth with milk and honey.
4 Hear , O Israel: The LORD our God is one LORD:
5 And thou shalt love the LORD thy God with all thine heart, and with all thy soul, and with all thy might.
6 And these words, which I command thee this day, shall be in thine heart:
The law concerning our responsibility must be in your heart, otherwise it means nothing. If we purposefully deny the instruction of God because His ways are no our ways, we are willfully ignorant, and willfully sinning. So then who is lawless? God's judgment is inescapable, and His judgments contain blessings as well as cursing. Do a Joshua and choose this day whom you will serve.