What is the duty toward those who remove their hijab in the name of opposing the system?

Yes, they fall within a degree of disbelief. One must dissociate oneself from their deeds, and the duty to enjoin what is right and forbid what is wrong must not be abandoned in their case, subject to its specific conditions.

One of the main pillars of disbelief is transgression, which includes every sin and violation. ( بُنِيَ الْكُفْرُ عَلَى أَرْبَعِ دَعَائِمَ- الْفِسْقِ وَ الْغُلُوِّ وَ الشَّكِّ وَ الشُّبْهَةِ ...)

The kind of disbelief under discussion consists in disobeying God’s commands and doing what He has forbidden.

The following tradition beautifully explains the different forms of disbelief:

Abu Amr al-Zubayri narrates from Imam al-Sadiq (AS): “I said to him, ‘Tell me: how many forms of disbelief are there in the Qur’an of God, Mighty and Majestic?’ He replied, ‘In the Book of God, disbelief takes five forms: denial—and denial itself takes two forms—disbelief through abandoning what God has commanded, disavowal, and ingratitude for blessings.

“As for disbelief by denial, it is the denial of Lordship. This is the position of those who say that there is no Lord, no Paradise, and no Hell. It is the belief of two groups of atheists, known as materialists, who also say (Surah al-Jathiyah, 45:24): “Nothing destroys us but time.” This is a religion they fashioned for themselves according to their own inclinations and preferences, without examining, investigating, or scrutinizing what they claim. God says of them (Surah al-Baqarah, 2:6): “Indeed, those who disbelieve—it is all the same to them whether you warn them or do not warn them; they will not believe.” This refers to disbelief in God’s oneness and in knowing God, Exalted is He. This is the first of the two forms of disbelief.

“The other form is denial despite knowledge: the denier knows that something is true, yet denies it, even though the truth has been established for him. God, Mighty and Majestic, says of this (Surah al-Naml, 27:14): “They denied them, though inwardly they were certain of them, out of wrongdoing and arrogance.” God, Mighty and Majestic, also says (Surah al-Baqarah, 2:89): “Although before this they had prayed for victory over the disbelievers through the coming of the Final Prophet, when what they recognized came to them, they rejected it. So God’s curse is upon the disbelievers.” This explains the two forms of denial.

“The third form of disbelief is ingratitude for blessings. God, Exalted is He, relates Solomon’s words (Surah al-Naml, 27:40): “This is by the grace of my Lord, to test me whether I will be grateful or ungrateful. Whoever is grateful is grateful for his own good, and whoever is ungrateful—surely my Lord is Self-Sufficient, Generous.” He also says (Surah Ibrahim, 14:7): “If you are grateful, I will surely increase you; but if you are ungrateful, surely My punishment is severe.” And He says (Surah al-Baqarah, 2:152): “Remember Me, and I will remember you. Be grateful to Me, and do not be ungrateful to Me.”

“The fourth form is abandoning what God, Mighty and Majestic, has commanded. This is what God means when He says (Surah al-Baqarah, 2:84–85): “And when We took your covenant: ‘Do not shed one another’s blood or drive one another from your homes,’ you affirmed it and bore witness. Yet here you are, killing one another and driving a group of your own people from their homes, aiding one another against them in sin and aggression. And if they come to you as captives, you ransom them, though their expulsion was forbidden to you. Do you believe in part of the Book and disbelieve in part? What, then, is the reward of those among you who do this?” God calls them disbelievers because they abandoned what He had commanded them. He ascribes faith to them, yet does not accept their faith or regard it as beneficial to them in His sight. He says: “The recompense for whoever among you does this is nothing but disgrace in the life of this world; and on the Day of Resurrection they will be returned to the harshest punishment. God is not unaware of what you do.”

“The fifth form of disbelief is disavowal. This is what God, Mighty and Majestic, relates from Abraham (AS) (Surah al-Mumtahanah, 60:4): “We reject you, and between us and you there has arisen enmity and hatred forever, until you believe in God alone”—that is, we disavow you. God also speaks of Satan’s disavowal of his human followers on the Day of Resurrection (Surah Ibrahim, 14:22): “Indeed, I disbelieved in your making me a partner with God before.” And God says (Surah al-‘Ankabut, 29:25):”

“Indeed, you have taken idols as objects of worship among yourselves in the life of this world. Then, on the Day of Resurrection, you will disown one another and curse one another”—that is, you will repudiate and shun one another.
*Uṣūl al-Kāfī*, Kamare’i translation, vol. 5, p. 409
عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنْ بَكْرِ بْنِ صَالِحٍ عَنِ الْقَاسِمِ بْنِ يَزِيدَ عَنْ أَبِي عَمْرٍو الزُّبَيْرِيِّ عَنْ أَبِي عَبْدِ اللَّهِ ع قَالَ: قُلْتُ لَهُ أَخْبِرْنِي عَنْ وُجُوهِ الْكُفْرِ فِي كِتَابِ اللَّهِ عَزَّ وَ جَلَّ قَالَ الْكُفْرُ فِي كِتَابِ اللَّهِ عَلَى خَمْسَةِ أَوْجُهٍ فَمِنْهَا كُفْرُ الْجُحُودِ وَ الْجُحُودُ عَلَى وَجْهَيْنِ وَ الْكُفْرُ بِتَرْكِ مَا أَمَرَ اللَّهُ وَ كُفْرُ الْبَرَاءَةِ وَ كُفْرُ النِّعَمِ فَأَمَّا كُفْرُ الْجُحُودِ فَهُوَ الْجُحُودُ بِالرُّبُوبِيَّةِ وَ هُوَ قَوْلُ مَنْ يَقُولُ لَا رَبَّ وَ لَا جَنَّةَ وَ لَا نَارَ وَ هُوَ قَوْلُ صِنْفَيْنِ مِنَ الزَّنَادِقَةِ يُقَالُ لَهُمُ الدَّهْرِيَّةُ وَ هُمُ الَّذِينَ يَقُولُونَ- وَ ما يُهْلِكُنا إِلَّا الدَّهْرُ “1” وَ هُوَ دِينٌ وَضَعُوهُ لِأَنْفُسِهِمْ بِالاسْتِحْسَانِ عَلَى غَيْرِ تَثَبُّتٍ مِنْهُمْ وَ لَا تَحْقِيقٍ لِشَيْ‏ءٍ مِمَّا يَقُولُونَ قَالَ اللَّهُ عَزَّ وَ جَلَّ- إِنْ هُمْ إِلَّا يَظُنُّونَ “1” أَنَّ ذَلِكَ كَمَا يَقُولُونَ وَ قَالَ- إِنَّ الَّذِينَ كَفَرُوا سَواءٌ عَلَيْهِمْ أَ أَنْذَرْتَهُمْ أَمْ لَمْ تُنْذِرْهُمْ لا يُؤْمِنُونَ يَعْنِي بِتَوْحِيدِ اللَّهِ تَعَالَى فَهَذَا أَحَدُ وُجُوهِ الْكُفْرِ وَ أَمَّا الْوَجْهُ الْآخَرُ مِنَ الْجُحُودِ عَلَى مَعْرِفَةٍ وَ هُوَ أَنْ يَجْحَدَ الْجَاحِدُ وَ هُوَ يَعْلَمُ أَنَّهُ حَقٌّ قَدِ اسْتَقَرَّ عِنْدَهُ وَ قَدْ قَالَ اللَّهُ عَزَّ وَ جَلَّ- وَ جَحَدُوا بِها وَ اسْتَيْقَنَتْها أَنْفُسُهُمْ‏ ظُلْماً وَ عُلُوًّا وَ قَالَ اللَّهُ عَزَّ وَ جَلَّ- وَ كانُوا مِنْ قَبْلُ يَسْتَفْتِحُونَ عَلَى الَّذِينَ كَفَرُوا فَلَمَّا جاءَهُمْ ما عَرَفُوا كَفَرُوا بِهِ فَلَعْنَةُ اللَّهِ عَلَى الْكافِرِينَ فَهَذَا تَفْسِيرُ وَجْهَيِ الْجُحُودِ وَ الْوَجْهُ الثَّالِثُ مِنَ الْكُفْرِ كُفْرُ النِّعَمِ وَ ذَلِكَ قَوْلُهُ تَعَالَى يَحْكِي قَوْلَ سُلَيْمَانَ ʿ—this مِنْ فَضْلِ رَبِّي لِيَبْلُوَنِي أَ أَشْكُرُ أَمْ أَكْفُرُ وَ مَنْ شَكَرَ فَإِنَّما يَشْكُرُ لِنَفْسِهِ وَ مَنْ كَفَرَ فَإِنَّ رَبِّي غَنِيٌّ كَرِيمٌ وَ قَالَ لَئِنْ شَكَرْتُمْ لَأَزِيدَنَّكُمْ وَ لَئِنْ كَفَرْتُمْ إِنَّ عَذابِي لَشَدِيدٌ وَ قَالَ فَاذْكُرُونِي أَذْكُرْكُمْ وَ اشْكُرُوا لِي وَ لا تَكْفُرُونِ وَ الْوَجْهُ الرَّابِعُ مِنَ الْكُفْرِ تَرْكُ مَا أَمَرَ اللَّهُ عَزَّ وَ جَلَّ بِهِ وَ هُوَ قَوْلُ اللَّهِ عَزَّ وَ جَلَّ- وَ إِذْ أَخَذْنا مِيثاقَكُمْ لا تَسْفِكُونَ دِماءَكُمْ وَ لا تُخْرِجُونَ أَنْفُسَكُمْ مِنْ دِيارِكُمْ ثُمَّ أَقْرَرْتُمْ وَ أَنْتُمْ تَشْهَدُونَ ثُمَّ أَنْتُمْ هؤُلاءِ تَقْتُلُونَ أَنْفُسَكُمْ وَ تُخْرِجُونَ فَرِيقاً مِنْكُمْ مِنْ دِيارِهِمْ تَظاهَرُونَ عَلَيْهِمْ بِالْإِثْمِ وَ الْعُدْوانِ وَ إِنْ يَأْتُوكُمْ أُسارى‏ تُفادُوهُمْ وَ هُوَ مُحَرَّمٌ عَلَيْكُمْ إِخْراجُهُمْ أَ فَتُؤْمِنُونَ بِبَعْضِ الْكِتابِ‏ وَ تَكْفُرُونَ بِبَعْضٍ فَما جَزاءُ مَنْ يَفْعَلُ ذلِكَ مِنْكُمْ فَكَفَّرَهُمْ بِتَرْكِ مَا أَمَرَ اللَّهُ عَزَّ وَ جَلَّ بِهِ وَ نَسَبَهُمْ إِلَى الْإِيمَانِ وَ لَمْ يَقْبَلْهُ مِنْهُمْ وَ لَمْ يَنْفَعْهُمْ عِنْدَهُ فَقَالَ فَما جَزاءُ مَنْ يَفْعَلُ ذلِكَ مِنْكُمْ إِلَّا خِزْيٌ فِي الْحَياةِ الدُّنْيا وَ يَوْمَ الْقِيامَةِ يُرَدُّونَ إِلى‏ أَشَدِّ الْعَذابِ وَ مَا اللَّهُ بِغافِلٍ عَمَّا تَعْمَلُونَ وَ الْوَجْهُ الْخَامِسُ مِنَ الْكُفْرِ كُفْرُ الْبَرَاءَةِ وَ ذَلِكَ قَوْلُهُ عَزَّ وَ جَلَّ يَحْكِي قَوْلَ إِبْرَاهِيمَ ع- كَفَرْنا بِكُمْ وَ بَدا بَيْنَنا وَ بَيْنَكُمُ الْعَداوَةُ وَ الْبَغْضاءُ أَبَداً حَتَّى تُؤْمِنُوا بِاللَّهِ وَحْدَهُ يَعْنِي تَبَرَّأْنَا مِنْكُمْ وَ قَالَ يَذْكُرُ إِبْلِيسَ وَ تَبْرِئَتَهُ مِنْ أَوْلِيَائِهِ مِنَ الْإِنْسِ يَوْمَ الْقِيَامَةِ- إِنِّي كَفَرْتُ بِما أَشْرَكْتُمُونِ مِنْ قَبْلُ وَ قَالَ إِنَّمَا اتَّخَذْتُمْ مِنْ دُونِ اللَّهِ أَوْثاناً مَوَدَّةَ بَيْنِكُمْ فِي الْحَياةِ الدُّنْيا ثُمَّ يَوْمَ الْقِيامَةِ يَكْفُرُ بَعْضُكُمْ بِبَعْضٍ وَ يَلْعَنُ بَعْضُكُمْ بَعْضاً يَعْنِي يَتَبَرَّأُ بَعْضُكُمْ مِنْ بَعْضٍ.
*Al-Kāfī* (Islamic edition), vol. 2, p. 389