Is money earned from selling household furniture and nude pictures and pictures of Christians' Jesus (peace be upon him) considered unlawful money (ill-gotten gain), and is it permissible to continue this work despite an urgent need for money?

You must advise your colleague regarding the impermissibility of selling nude and forbidden images. Your work with him is permissible if it is limited to selling permissible items. However, if it entails selling forbidden items, then it is not permissible. The ruling on the past salaries you received will be detailed based on that.