Assalaamu Alaykum dear brother,
There is a difference of opinion on this matter with scholars on both sides and good arguments on both ends.
My teachers and colleagues are of the view that it depends on multiple factors and a one-size-fits-all answer does not always work.
With regard to seeking a job, as a principle, one should seek to be employed in a Shariah compliant firm. Islam is a values-based system of life and we should seek to be in places which align with the values and morals we believe in. This is not a Fatwa matter, rather general guidance for everyone. I do not think anyone would disagree on this matter. However, when it comes to application, we must consider the different variables and realities at play. This is precisely the role of a Mufti and someone who has studied the principles of giving Fatwa will be aware of this. The situation in Muslim minority countries is somewhat difficult. We have extremely talented individuals and highly skilled people who cannot find Shariah compliant firms (partly due to the lack of them and secondly due to the competition being so fierce). Secondly, many such talented Muslims go on to greater things and move over to develop Islamic finance years later with the experiences they have gained in the industry. Further, people who are qualified in finance usually go on to seek employment in the finance sector. Changing sector or moving to a low-pay job after years of study is unreasonable. That being said, my view, and the view of many colleagues and that of our teachers in South Africa is that on condition that the job description is permissible and one is not involved in any non-Shariah compliant matter in their role, there is scope to apply for a role in a conventional firm for Muslims in minority countries in challenging employment circumstances.
This is based on the view of Imam Abu Hanifah whose principle is that one is only responsible for the actual role and job they are doing and the lawfulness of the income is directly correlated to that only. Hence, if you are doing only halal activities, your role is lawful and your income is halal. Of course, if there are viable opportunities to move over to a sector or department which is premised on Shariah compliance, that is always the best.
If a person’s job description is unlawful, he cannot even work in a halal industry let alone the conventional finance industry.
So to summarise, from a FIQHI/TECHNICAL sense, the job description and role will determine how remote or in proximity you are to unlawful activity. If your job description clearly involves impermissible activity, you are in proximity to unlawul activity and your job is not Shariah compliant. If your job does not involve any non-Shariah compliant activity or service, your role is lawful, your income is lawful and you are remote from non-compliant activity.
The following references are key to this discussion:
في رد المحتار على الدر المختار
(قَوْلُهُ وَجَازَ تَعْمِيرُ كَنِيسَةٍ) قَالَ فِي الْخَانِيَّةِ: وَلَوْ آجَرَ نَفْسَهُ لِيَعْمَلَ فِي الْكَنِيسَةِ وَيُعَمِّرَهَا لَا بَأْسَ بِهِ لِأَنَّهُ لَا مَعْصِيَةَ فِي عَيْنِ الْعَمَلِ (ج 6 ص 391 أيج أيم سعيد)
وفي الفتاوى الهندية
مُسْلِمٌ آجَرَ نَفْسَهُ مِنْ مَجُوسِيٍّ لِيُوقِدَ لَهُ النَّارَ لَا بَأْسَ بِهِ. كَذَا فِي الْخُلَاصَةِ. (ج 4 ص 450 دار الفكر)
وفي فتاوى قاضي خان
لو أن مسلما آجر نفسه ليعمل في الكنيسة و يعمرها لا بأس به لأنه لا معصية في عين العمل (ج 3 ص 330 دار الكتب العلمية)
في حاشية ابن عابدين
(قَوْلُهُ وَجَازَ إجَارَةُ بَيْتٍ لِيُتَّخَذَ بَيْتَ نَارٍ أَوْ كَنِيسَةً أَوْ بِيعَةً أَوْ يُبَاعَ فِيهِ الْخَمْرُ) هَذَا عِنْدَهُ أَيْضًا لِأَنَّ الْإِجَارَةَ عَلَى مَنْفَعَةِ الْبَيْتِ، وَلِهَذَا يَجِبُ الْأَجْرُ بِمُجَرَّدِ التَّسْلِيمِ، وَلَا مَعْصِيَةَ فِيهِ وَإِنَّمَا الْمَعْصِيَةُ بِفِعْلِ الْمُسْتَأْجِرِ وَهُوَ مُخْتَارٌ فَيَنْقَطِعُ نِسْبِيَّتُهُ عَنْهُ (ج 6 ص 392 ايج ايم سعيد)