Why Tithe?

What is a tithe? It comes from the Anglo-Saxon word teotha, meaning a tenth. Generally, it has been defined as the "tenth part of the increase arising from the profits of land and stock, allotted to the clergy for their support or devoted to religious or charitable uses". However, there have been tithes long before there were "clergy" in the Christian sense. So a more biblical definition is "the tenth part of all fruits and profits justly acquired, owed to God in recognition of his supreme dominion over man, and to be paid to the ministers of the church". 

Photo from 5 Ps of Giving

As Christians, we are cultivating a heart of generosity like Christ's. Tithes are one way to do this. There are others. That is why  the Catechism of the Catholic Church emphasizes, not a particular amount of method of tithing, but the general demand of generosity:  

2449. Beginning with the Old Testament, all kinds of juridical measures (the jubilee year of forgiveness of debts, prohibition of loans at interest and the keeping of collateral, the obligation to tithe, the daily payment of the day laborers, the right to glean vines and fields) answer the exhortation of Deuteronomy:   

"For  the   poor  will  never cease out of the land; therefore I command you, 'You shall open wide your hand to your brother, to the needy and to thepoor in the land.'''[Deut 15:11 .]   

Jesus makes these words his own: 

"The poor you  always  have with you, but  you do not   always have me."[Jn 12:8 .] 

In doing so, he does not soften the vehemence of former oracles against "buying the poor for silver and the needy for a pair of sandals ...,

"but invites us to recognize his own presence in   the poor who are his brethren: [Am 8:6;cf.Mt25:4.]

In the end, is the answer to the question of "why?". For the fact is that in tithing we are giving to Christ (or rather, giving back to Christ). It's as simple as that.

Source:An Excerpt from EWTN National Catholic Register, "Why Tithe?"