What is the ruling on working in a company managed by Christians and employing Christians in the field of engineering and construction, and what is the ruling on working with them in any field to earn a lawful livelihood?

There is no objection to a Muslim working for a company managed or owned by a disbeliever if the field of work is permissible and the wage is lawful, and provided that the nature of the work does not involve humiliation or degradation for the Muslim.