Summary: Why Do Christian Preachers teach an Old Covenant practice that only applied to Israel and the care of the Levites that didn't have a land inheritance?
"Will a man ROB God?" How many untold tens of thousands of men will give account one day for teaching this verse in Malachi 3:8 totally out of context for their own sordid gain. I couldn’t count the times I have heard self-appointed ministers of the gospel berate their congregations and listeners for "robbing God" in tithes and offerings. This verse in Malachi certainly means what it says. Someone was defrauding God of tithes and offerings, but wait until you find out who it is that God blames for this act.
On any given Sunday morning there will be numerous men-of-the-cloth who will be bellowing out over the air waves that people are being "cursed with a curse" because they have failed to pay God ten percent of their paychecks. And should such a gullible listener decide to repent and give God ten percent of his salary, just how would he do that? Just keep reading. These men of the cloth who often have unquenchable worldly desires of the flesh, will be sure to give you an address where you can send them (or, ah, rather God) your tithe. And do they have a right to quote these Scriptures in this manner? No they do not, and furthermore they themselves know better.
SOME SHOCKING TRUTHS ABOUT THE CHRISTIAN TITHING DOCTRINE
Abraham never tithed on his own personal property or livestock.
Jacob wouldn’t tithe until God blessed him first.
Only Levite priests could collect tithes, and there are no Levite priests today.
Only food products from the land were tithable.
Money was never a tithable commodity.
Christian converts were never asked to tithe anything to the Church.
Tithing in the Church first appears centuries after completion of the Bible.
ALL SCRIPTURAL REFERENCES TO TITHING
We will now go through all the Scriptural references in the Bible on tithe, tithes, and tithing:
 Gen. 14:20, "And blessed be the most high God, which hath delivered thine enemies into thy hand. And he [Abram] gave him [Melchizedek king of Salem, the priest of the most high God, Ver. 18] TITHES of all [all the goods of war, Ver. 16]."
We read again of this same event in the book of Hebrews:
 Heb. 7:1-10, "For this Melchizedek, king of Salem, priest of God Most High, who meets with Abraham returning from the combat with the kings and blesses him, to whom Abraham parts a TITHE also, from all... Now, behold how eminent this one is to whom the patriarch Abraham gives a TITHE also of the best of the booty. And, indeed, those of the sons of Levi who obtain the priestly office have a direction to take TITHES from the people according to the law... And here, indeed, dying men are obtaining TITHES... And so, to say, through Abraham, Levi also, who is obtaining the TITHES, has been TITHED, for he was still in the loins of his father when Melchizedek meets with him."
There are a number of things we can learn concerning tithing from this section of Scriptures. In this, the first mention of tithing in the Bible, Abram gives to Melchizedek (a priest of God who was also the king of the city of Salem) a tithe of the best of the booty taken in war. Notice that this was not wheat, corn, wine, oil, or cattle from Abram’s personal possessions, but rather booty taken from conquered nations.