What is the Shar'i criterion for obtaining lawful employment in a Western country, taking into consideration the prevalence of doubtful and Sharia-prohibited matters in the available jobs, and the inability to easily leave a job?

Religion makes things easy for its servants and does not burden them. If a person thinks in this way, he will not find any permissible work; because human endeavors are interconnected and may involve prohibited acts, but that does not mean that work originally permissible becomes forbidden.

For example, a mobile phone vendor cannot be prevented from selling phones if some people use them for forbidden purposes, nor can a clothing vendor be prevented if some women wear them in a forbidden manner.

Therefore, you must seek a suitable permissible job for yourself and avoid two types of work: 1. Work that is inherently forbidden: Such as working in the sale of alcohol and pork, usurious banks, and the like. 2. Work that directly aids in forbidden acts: Such as serving alcohol to those who drink it, and writing usurious contracts.

However, if the aid is indirect or merely a suspicion, that does not make the work forbidden, especially if the person does not intend the forbidden in his work.