Jesus made it absolutely clear that no one can serve both God and mammon. A person will love one and hate the other. However, many in the modern church fail to take this literally and even perhaps twist the verse to mean that one can love mammon as long as one uses mammon to glorify God, using 'mammon' to mean money. Indeed, money can be used to buy things that are used to serve God, such as a church building, Bibles and setting up an evangelical radio network. However, this is a very dangerous half-truth. It is not the money that glorifies God, neither is it the things that one does using money that glorifies God. It is the heart right with God that God is after (Matthew 23:27).
The attitude of the modern church is that because money can be used sacrificed to serve God, it is not wicked in itself. That is true that money is not wicked in itself, but it is not the sacrifice of money to glorifies God. Rather, it is obedience to God alone. Hath the LORD as great delight in burnt offerings and sacrifices, as in obeying the voice of the LORD? Behold, to obey isbetter than sacrifice, and to hearken than the fat of rams (1 Samuel 15:22).Since a person can only either love God and hate mammon, or love mammon and hate God, it is absolutely unbiblical to claim that because money can be used to 'good' that there is nothing wrong with accumulating money and earthly things. Accumulating earthly things IS to serve mammon.
Jesus did command His followers to "sell your possessions and give to the poor. Provide purses for yourselves that will not wear out, a treasure in heaven that will never fail, where no thief comes near and no moth destroys" (Luke 12:33), not just the rich young ruler in Matthew 19:21 as many Christians claim. This was because "for where your treasure is, there your heart will be also" (Luke 12:34).
Where one's heart is with earthly things, one will serve earthly things. One will seek for such things as that is where one's treasure is located. Where one's heart is with God, one will serve God. One will seek first the Kingdom of God as there is where one's treasure is located. This is why Jesus commanded His followers to "seek ye first the kingdom of God" (Matthew 6:33). Only when one seeks to serve God first that His righteousness and the material needs will be added onto you (Matthew 6:33). However, many Christians in the mammonised West argue that while one needs to serve God, one also needs to protect and seek one's material needs, in addition to serving God. How can one serve God when one is striving anxiously to serve one's material needs? How? When one seek to serve one's own material needs, one IS in the flesh. Such is selfishness and disobedience. The root of this is anxiety. The root from which anxiety grows is pride in one's own self, which mammon feeds off.