Romans 3 v 28 Therefore we conclude that a man is justified by faith without the deeds of the law. 29 Is he the God of the Jews only? is he not also of the Gentiles? Yes, of the Gentiles also: 30 Seeing it is one God, which shall justify the circumcision by faith, and uncircumcision through faith.
31 Do we then make void the law through faith? God forbid: yea, we establish the law.
Romans 13 v 3 For rulers are not a terror to good works, but to the evil. Wilt thou then not be afraid of the power? do that which is good, and thou shalt have praise of the same: 4 For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil. 5 Wherefore ye must needs be subject, not only for wrath, but also for conscience sake. 6 For for this cause pay ye tribute also: for they are God’s ministers, attending continually upon this very thing. 7 Render therefore to all their dues: tribute to whom tribute is due; custom to whom custom; fear to whom fear; honour to whom honour.
So for Paul both rulers and the gospel of grace are instrumental to the establishing of the law: one to justify and the other to condemn and punish. The law which Paul has in mind is of course the law given to Moses at Mt. Sinai. The same law works in different ways to the benefit of mankind and the glory of God.
The Sharia law of Mohammed is a late invention of man, which plagiarized various sources, and did not originate from God.