It depends on which Law you are talking about. As New Covenant believers, the Law of Moses no longer applies - all 613 commandments (which includes the Ten Commandments – see 2 Cor. 3:7). It has been rendered useless. Because Christ is the end of the Law (Rom. 10:4), the Mosaic Law is now void as it cannot serve in justification nor sanctification (Heb. 7:18-19 and Gal. 2:16). Yet, Christians are now under the Law of Christ (Gal. 6:2 and Rom. 8:2). Typically there is confusion among believers as to which of the OC laws we are “still” under, this being due to the fact that there are some similarities between the two Laws. However, these commandments are still two distinct and separate systems with two entirely different purposes.
You mentioned that you've been conversing with a Seventh Day Adventist (been there...) so I would steer him/her to James 2:10. While modern-day bibles divide up the Law into ceremonial, legal, and moral commandments for the ease of study, the Mosaic Law was in reality viewed as one single unit without division.
My thoughts on the "2 laws" I believe is how they come about....for lack of better wording.
Under the old Cov, just maybe love couldn't be kept in terms of ourselves...because it wouldn't be genuine. Another words the love would need to stem from true love. How then could love come from a place of condemnation...but let me look at the law under the old Cov just to see how it is written. Another thought is How can you love without first having love or a pure heart.
However under the new covenant Faith in Christ "produces" for lack of better word love.
It makes you want to love as for the connectivity of the relationship, even forgiveness, peace, joy, life, are part of having a connection through faith. After you see what you get from that connection...sometimes even that is the force behind why we want to love. To Sum it up God is behind it all, but there is a way we must come to Him......sometimes wonder if he has a body soul and spirit..or rather parts that like a human relationship that allow a person into his heart.
I can't say we are given the Spirit to keep the law..But we know the law is kept having followed after the leading of the Spirit. For we know when we walk in the Spirit the blood of Jesus cleanses us from all sin.
So you said, The Law of Moses could not justify us nor sanctify....But why do you add sanctify. For isn't sanctification away of not only purifying ourselves through our walk...but also staying away from things that lead others from entering the kingdom?
My first thought was we are given the Spirit to hold up or establish the law.
For without holding up to its standards how shall one have peace with God. Therefore by the inside being clean the outside is too...
The Law of Moses were things that were done out of our own power...yet the flesh was taken over by Satan that we became creatures of habit.
Anyway, I would not say one is given the Spirit of Christ to stive to keep the law. Yet we fullfill the law as Christ did when we walk by the spirit. For we are all the body of Christ...therefore it would be fitting for us to comform to his likeness.
Those are my thoughts let me know what you think.
Peace and blessings to all that are living to have purpose to lift up the name of Jesus...
For He said if I be lifted up from the earth He would draw ALL men unto himself.