If a non-Muslim living in full by means of usury business invites me for food in his house, can I go and eat his food? If yes, then may I know the proofs that conclude such results?
The Shari`ah has not dealt with the issue specifically. Therefore, our conclusion will be based on Ijtihād considering the principles of the religious guidance in this regard. We believe that there is nothing wrong in accepting such an invitation and eating food offered by a non-Muslim. If we close the door for such an interaction then there remains no chance of propagation of the religion and dialogue between Muslims and the members of other religions. The Prophet (sws) has been visiting the people of the other faith and eating with them without probing into the source of the income of those individuals. However, the host offers you something that is clearly held harām by the Shari`ah for example pork etc. you may ask his excuse. We are not allowed to take any harām thing in normal circumstances.