In the New Testament Jesus states that you can't serve "both God and Mammon". Some have identified Mammon is as a god/demon of money, wealth or greed. The word mammon may simply have meant "money" or "wealth" however.

Ploutos or Plutos was the Greek god of wealth.

Mammon symbolizes money or material wealth. Mammon as a god has no existence outside of the Bible.

Mammon is a lie, like cheating in a card game

It's difficult if not impossible to serve God and mammon, because if you are serving your own worldly gain, then God is not the center nor the most important part of your life. Ultimately, if you are a true Christian the only thing that should matter is total surrender to God's will. Money, prestige, etc. can control people. Everyone is controlled by something or someone, whether they like it or not, and whatever controls you is ultimately your "god", and therefore you serve it.

Mammon