I say despite their faith in Jesus, because Paul was referring to immoral Christians, and not Pagans.
I don't see anything immoral about Christians going to secular judges. The irony is that we will judge the world and fallen angels yet they go to unbelievers to sort out their affairs.
I can only suggest you reread the passage, then read the passages that make it clear that we have, in Christ—been made complete in regards to remission of sins:
Hebrews 10:1
King James Version
1 For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.
Hebrews 10:14
King James Version
14 For by one offering he hath perfected for ever them that are sanctified.
While in a temporal context we still sin and are in need of confession and remission of sins, in the Eternal Context we have been forgiven forever. Is that not what the Writer of Hebrews states above?
And He doesn't say "The Moral Law was a shadow of the good things to come," he says quite clearly he is speaking about The Law.
This is why the Priesthood and The Law was changed. Because the New Covenant is not based on an If/Then condition. It is based on an I will condition:
Ezekiel 36:24-27
King James Version
24 For I will take you from among the heathen, and gather you out of all countries, and will bring you into your own land.
25 Then will I sprinkle clean water upon you, and ye shall be clean: from all your filthiness, and from all your idols, will I cleanse you.
26 A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.
27 And I will put my spirit within you, and cause you to walk in my statutes, and ye shall keep my judgments, and do them.
When we walk in His statutes, and keep His judgments—we do so by His power. The power of God working in our lives.
Not by good works which we have done.
So the first step to "keeping the Law" is that one must be eternally indwelt by God.
But it still remains: we are not under Law. We are in relationship with God through Christ under the New Covenant:
Hebrews 8:8-13
King James Version
8 For finding fault with them, he saith, Behold, the days come, saith the Lord, when I will make a new covenant with the house of Israel and with the house of Judah:
9 Not according to the covenant that I made with their fathers in the day when I took them by the hand to lead them out of the land of Egypt; because they continued not in my covenant, and I regarded them not, saith the Lord.
10 For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
11 And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.
12 For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more.
13 In that he saith, A new covenant, he hath made the first old. Now that which decayeth and waxeth old is ready to vanish away.
Nothing about moral or Levitical law here. Just a matter of what God is going to do in the lives of men and women.
While the context is specific to the formalized Covenant of Law (the "First Covenant," which was not the first in a meaning of sequence), being under Law extends to the "Law" of God prior to the Covenant of Law.
We see that example here in regards to vicarious animal sacrifice (which also predates the Covenant of Law):
Hebrews 12:18 & 22-24
King James Version
18 For ye are not come unto the mount that might be touched, and that burned with fire, nor unto blackness, and darkness, and tempest,
22 But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels,
23 To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect,
24 And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel.
All covenants of the Old Testament prophesied of the New Covenant, and were but shadow, and parable.
Paul makes a clear point here:
Galatians 3:10
For as many as are of the works of the law are under the curse: for it is written, Cursed is every one that continueth not in all things which are written in the book of the law to do them.
If one wants to be under Law, even if they try to give it a sugary coating by calling it "Moral Law," then they are still under the curse.
Because...
James 2:10
For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all.
So my question at this point would be, just how well are you doing in keeping the Moral Law, my friend?
Are you keeping it perfectly? Have you failed to keep it even once? If so then you are lost, because you are guilty of all the Law.
Regardless of whether it is Moral Law or Levitical Law.
Continued...