Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour (1 Peter 5:8).
Jesus made it clear that no one can serve both God and mammon. One will be devoted to one and hate the other. This means that not only is materialism hostility against God, but the yielding to the seducing voice of mammon and embracing his voice is hostility against God. There is absolutely no middle ground. A person either serves God, or serves mammon. Those who try to do both, as many Christians are trying to do are being lead by satan to the broad road, but God is there to stop them from stepping onto the broad road that leads to Hell. They are trying to step onto the broad road, but God is holding them back if they are true converts.
However, that God holds back the true Christian from stepping onto the broad road to Hell does not in any way provide an excuse to even attempt to serve both God and mammon. The thought that one can serve both God and mammon alone is to disregards the words of Jesus as such a thought directly contradicts Jesus' words that "If any man will come after me, let him deny himself, and take up his cross, and follow me" (Matthew 16:24). This means to completely surrender own's life for Jesus. It is a continuing process that is to be renewed at the start of each day - to give up one's rights, interests, aspirations, freewill, dreams and visions to follow Jesus. It is to cut oneself from anything that can tie oneself to mammon, the spirit behind all earthly things.
To serve mammon is to cut oneself off from Christ because mammon is a spirit that tempts people to serve the flesh. Such things which serve the flesh are earthly things which will rot, and which have no Eternal value. The value of all earthly things are non-existent in reality, and existent only to the eyes of the beholder. Such things, including all earthly duties, tempt people to serve themselves first, and lure them into the Pits of Hell.