These are very common questions I have been asked. Indeed, they are good questions.
The spirit of mammon is behind everything opposed to God. Jesus Himself said that "No one can serve two masters. Either you will hate the one and love the other, or you will be devoted to the one and despise the other. You cannot serve both God and money" (Matthew 6:24). But, you may say, there is no 'spirit of mammon'. Ephesians 6:12 tell us that we fight against principalities and powers. These are spiritual forces of darkness from satan: For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.