I think this quote from the sermon does a good job of explaining the law for the Christian:
" What is God's law now? It is not above a Christian-it is under a Christian. Some men hold God's law like a rod, in terrorem, over Christians, and say, "If you sin you will be punished with it." It is not so. The law is under a Christian; it is for him to walk on, to be his guide, his rule, his pattern. "We are not under the law, but under grace." Law is the road which guides us, not the rod which drives us, nor the spirit which actuates us. The law is good and excellent, if it keeps its place.”
This sermon helps me better articulate how the Law and Gospel work together. Not to mingle them but see their correct place, not by minimizing either but seeing God’s plan under the New Covenant for each.
When seen in light of the New Covenant (Jer 31:31ff) we see that the law is not abrogated (antinomianism) but is followed out of love and devotion for God not out of working for acceptance. His law is not burdensome (1 Jn 5:1-5) because we are not the ones that have to find the strength to follow it.
I was reading an article by Tom Ascol (A Neglected Topic for Needy Times )on this subject and came across this prayer from John Calvin:
Grant, Almighty God,
that as thou hast made known to us thy Law,
and hast also added thy Gospel,
in which thou callest us to thy service,
and also invitest us with all kindness to partake of thy grace,--
O grant, that we may not be deaf,
either to thy command or to the promises of thy mercy,
but render ourselves in both instances submissive to thee,
and so learn to devote all our faculties to thee,
that we may in truth avow that a rule of a holy and religious life
has been delivered to us in thy law,
and that we may also firmly adhere to thy promises,
lest through any of the allurements of the world,
or through the flatteries and crafts of Satan,
thou shouldest suffer our minds to be drawn away from that love
which thou hast once manifested to us in thine only-begotten Son,
and in which thou daily confirmest us
by the teaching of the Gospel,
until we at length shall come to the full enjoymentof
this love in that celestial inheritance,
which has been purchased for us by the blood of thy only Son.
The fact we are under grace does not remove the law but lets us relate to it in a better and grace related manner.