What is serving Mammon?

"This is so wrapped up with that phase of "the pride of life” —ambition, self-exaltation, self aggrandizement, gloriosus,—that it is, in great measure, inseparable from it. 

For there is nothing that gives worldly glory so quickly, so easily, and so abundantly as money; and there is nothing that gives power so quickly and so easily as does money. 

---All this, simply because Mammon is such a familiar deity to mankind, because mankind is naturally so worshipful of Mammon. And yet it is all idolatry; it is all a denial of the true God; it is a breaking of the First Commandment, which says, "Thou shalt have no other gods before Me.” For, says Jesus: "Ye can not,"—not, Ye ought not; not, Ye should not; but,—"Ye can not serve God and Mammon."
Since the true worship of God is to love God with all the heart, and all the soul, and all the mind, and all the strength; and anything that draw away either the heart, soul, mind, or strength to it, and comes between man and the true worship of God, is another god; so the allowing of money, the desire for money, the love of money, to come between a man and his true service to God, is the worship of Mammon." 

E.J. Waggoner