Is it permissible for a Muslim to work under an invalid system with the intention of calling to Allah (Blessed and Exalted is He)?

The questioner : The third question: Is it permissible for a Muslim to work under an invalid system with the intention of calling to Allah (Blessed and Exalted is He)? For example, working in an interest-based institution or a shop for intoxicants? And is it permissible for him to occasionally visit places of evil, such as houses of prostitutes, with the intention of calling them to the truth and advising them, or is it not?

The Shaykh : This question contains two questions: The first is: Is it permissible to be an employee in the state?

Eid Abbasi : An interest-based institution.

The Shaykh : Yes?

Eid Abbasi : An interest-based institution for the sake of enjoining good.

The Shaykh: Yes.
Is it permissible to work in an invalid system with the intention of calling to the truth; for example, working in an interest-based institution, and so on?
I think the answer to this question can be taken from the two previous answers, but some detail is necessary:
There is nothing in Islam that the rulers of this age, the disbelievers explicitly and the Muslim rulers who follow them, practice. We do not have in Islam the idea that the end justifies the means. Therefore, a Muslim is not permitted to engage in an evil matter in order to achieve a good matter. Working in an interest-based institution is not permissible in Islamic law, no matter what is claimed about the intention behind this work being a good and noble intention. How can one who believes in Allah and His Messenger consider himself obedient to Allah while he performs an act for which the Messenger of Allah (peace and blessings be upon him) cursed him?!
And by this I mean referring to the authentic hadith, in which he (peace and blessings be upon him) said: . In this hadith, the scribe is cursed, and that is only because he cooperates with the consumers of usury, and they deserve the curse. So this scribe deserved the curse with them because he helps them in their evil. There is no justification in Islam for a means that is religiously evil for the sake of a noble end—as they claim!—which is calling to Islam, or serving Islam through this unlegitimate path. So we say: Every Muslim who is compelled to live under a state that does not rule by Islam must choose from the jobs and positions what Islam does not forbid, and then he is able at the same time to call to Islam through the very job in which he works.
As for the second part of the question, which is: Is it permissible to visit places of prostitutes occasionally with the intention of calling them to the truth?
The answer is: If he guarantees two things, then the ruling is that it is permissible. The first thing: that he does not get involved, such as being a young man—for example—who is still in the prime of his youth, so that he does not get involved because of his occasional visits to those places and becomes tempted by the prostitutes. He goes to reform them, and then he falls into their corruption. If he guarantees this first, and guarantees another thing: that people do not talk about him as if he visits these places with the intention of committing fornication, and that he does not intend mere calling to the truth; because this visiting cannot be revealed for its true nature as long as it is a place of obscenity, and the prostitutes are the majority of the darkness of this visitor to that place with the intention of calling to the truth.
Therefore, I say: This visiting itself, in my view, is no different from visiting places of disbelief and shirk (associating partners with Allah) with the intention of calling to the truth, but we should observe the two matters mentioned above in both cases.

The questioner : May Allah reward you with good.