I am an employee in a non-Muslim bank. My work entails marketing and promoting the bank.

Answer

Banks are institutions of riba. They are the worst shayaateen in this field. Regardless of the capacity you are working in, you are aiding a riba institution – a haraam enterprise. A farmer who is not involved in making liquor, grows grapes specifically for a winery. He has a contract with the winery. It is haraam for him to grow grapes for this purpose, and it is haraam to sell the grapes to the winery. His argument of not being involved in the actual manufacture of the liquor is baseless. He is an active conniver in sustaining the haraam winery. Similarly, you are an active conniver promoting the riba institution. In fact, riba is worse than liquor. Your job is not permissible. It is in flagrant violation of the Qur'aanic prohibition: "Do not aid in sin and transgression."