In His Sermon on the Mount Jesus speaks of building one’s house's foundation upon sand or upon rock. Those who build on sand do so only on visible and tangible things: on success, career and money. These may seem as true reality, but one day they will pass away. We see this happening today with our collapsing economic systems. Money disappears, it becomes nothing. And thus all these things which seem to be real and upon which we can rely, are in fact of secondary importance to God Who is infinite and stable like Heaven.
Avarice, or greed, is the inordinate love of earthly goods. To understand this disorder it is important to recall the end for which God has given man temporal goods.
God's purpose is twofold: our own personal benefit and that of our bothers. Earthly goods are given to us to minister to our own temporal needs of body and soul, to preserve our life and the life of those dependent upon us, and to procure the means of cultivating our minds and developing our other faculties. Hence it is not forbidden to desire material goods, so long as we use them accordingly while also giving a due share to the poor and to good works - keeping always in mind that it is our duty to acquire these goods through honest work.
The disorder in loving earthly goods at times lies in the intention. This is the case when we desire wealth for its own sake, as an end in itself, or for other purposes which we ourselves set up as our ultimate end, for instance, to seek pleasure and honors. When we fail to see in riches means to higher ends we become guilty of idolatry.
The disorder further manifests itself in the manner of seeking riches: we pursue them with eagerness and without regard for the rights of others, to the detriment of our health or that of others, by hazardous speculations at the risk of losing all our savings.
The disorder likewise shows itself in the way we use money: 1) we spend it niggardly because we want to accumulate it in order to feel more secure, or to wield the influence, power and control, that come with riches. 2) We give little or nothing to the poor or the common good. 3) Some reach the point where they love their money so much that they actually enjoy feeling it. This immediately brings to mind the idolatrous miser Ebenezer Scrooge whose "business" occupied him constantly.
While the fault of avarice can infect anyone, it tends to show itself in middle life or old age when the fear of want develops more keenly, based sometimes on the thought of sickness or accidents that might incapacitate one for work. Bachelors and spinsters are particularly exposed to avarice, since they have no offspring to care for them in old age.
Avarice is a sign of mistrust in God and in his Divine Providence: "Behold the birds of the air, for they neither sow, nor do they reap, nor gather into barns: and your heavenly Father feedeth them. Are not you of much more value than they? ...how much more you, O ye of little faith?" (Matthew 6: 26,30). The greedy man puts his trust not in God but in the abundance of his riches. And he insults God in doing so: "Behold the man that made not God his helper: But trusted in the abundance of his riches: and prevailed in his vanity." (Ps. 51:9). This lack of confidence in God is accompanied by too great a confidence in self and personal effort. Jesus thus reminds us: "No man can serve two masters. For either he will hate the one, and love the other: or he will sustain the one, and despise the other. You cannot serve God and mammon" (Matthew 6: 24).
For the reasons just adduced avarice is considered a grave sin. It is likewise grave when it causes one 1) to infringe upon important rights of others by deceitful means in order to obtain and retain wealth; 2) to sin against charity by forgoing almsgiving; or 3) to fail against religion by becoming obsessed with business to the point of neglecting one's religious duties. Avarice constitutes a venial sin when it does not cause one to fail in any of the great Christian virtues or in one's duties to God.
Seek after heavenly riches, not earthly ones
Avarice is a serious obstacle to perfection. It is a passion that tends to supplant God in the human heart (God's temple) with earthly desires, anxieties and distracting preoccupations. Anyone in the grip of avarice soon becomes a slave to the maintenance, organization, storage, care and keeping of the quantities of things they own. Yet, to be united with God we need to free ourselves of all worldly creatures and cares. God wants us to love Him undividedly with all our mind, heart, soul, strength and being (cf. Matthew 12: 30). To fasten our heart on riches is to hinder the love of God, for where our heart is there is also our treasure.
Avarice is also an impediment to perfection because it leads to lack of mortification and to sensuality. It is therefore, necessary to conquer this vice. The remedy for greed/avarice lies in the conviction that wealth is not an end, but a means given us by Providence to provide for our needs and the needs of others; that God ever remains the Sovereign Master of all; that we are in truth only administrators who must one day render an account to the Sovereign Judge. We came into this world with nothing and we leave with nothing. If we are wise we will lay up treasure not for this world but for the next: "Lay not up to yourselves treasures on earth: where the rust, and moth consume, and where thieves break through and steal. But lay up to yourselves treasures in Heaven: where neither the rust nor moth doth consume, and where thieves do not break through, nor steal" (Matthew 6:19-20).
The most effective way of detaching ourselves from riches is to invest our wealth in the bank of Heaven by giving generously to the poor and to good works. A gift to the poor is a loan to God; it yields a hundredfold even in this world, in the joys which come to us from giving happiness to those around us. But above all, it yields a hundredfold for heaven, where Christ will give us imperishable goods in exchange for those we sacrifice for Him: "Seek ye therefore first the kingdom of God, and his justice, and all these things shall be added unto you" (Matthew 6: 33).