No man can serve two masters: for either he will hate the one, and love the other; or else he will hold to the one, and despise the other. You cannot serve God and mammon.
All Commentaries on Matthew 6:24 Go To Matthew 6
Now Jesus calls mammon here “a master,” not because of its own nature but on account of the wretchedness of those who bow themselves beneath it. So also he calls the stomach a god, not from the dignity of such a mistress but from the wretchedness of those enslaved. To have mammon for your master is already worse itself than any later punishment and enough retribution before the punishment for any one trapped in it. For what condemned criminals can be so wretched as those who, once having God for their Lord, do from that mild rule desert to this grievous obsession for money? Even in this life such idolatry trails immense harm in its path, with losses unspeakable. Think of the lawsuits! The harrassments, the strife and toil and blinding of the soul! More grievous, one falls away thereby from the highest blessing—to be God’s servant. The Gospel of Matthew, Homily