So, does that mean when I was 12 and cut my first yard for hire and made 2.50 and tithed 25 cents, my tithing days were fulfilled? After all I tithed once!
No, Abraham already "fulfilled" the tithe for the Melchizedek priesthood.
No, Jesus' one-time sacrifice as a priest after the order of Melchizedek was final, and Abraham's one-time tithe to Melchizedek functioned as a confirmation of this priestly order.
The Levitical tithes were necessary to sustain the limited, physical lives of the order of Levites who received a portion of the tithes as their food and the rest for the priests. The priests also used part of the tithes from the Levites as food and the rest for burnt offerings.
Because the offerings were constant and perpetual, so the tithes were necessary to sustain this imperfect priestly practice. Jesus performed the ultimate sacrifice of Himself once for all time.
Heb 7:26 For such an high priest became us, who is holy, harmless, undefiled, separate from sinners, and made higher than the heavens;
Heb 7:27 Who needeth not daily, as those high priests, to offer up sacrifice, first for his own sins, and then for the people's: for this he did once, when he offered up himself.
Jesus is seated in the heavenlies. His priestly function is powerful and effectual to save His people to the uttermost. His priesthood is not after the law of a carnal commandment: perpetual imperfect sacrifices and perpetual need for a supply of food through tithes. His perfect priestly sacrifice is perfect and needs no tithes:
Heb 8:1 Now of the things which we have spoken this is the sum: We have such an high priest, who is set on the right hand of the throne of the Majesty in the heavens;
Heb 8:2 A minister of the sanctuary, and of the true tabernacle, which the Lord pitched, and not man.
Heb 8:3 For every high priest is ordained to offer gifts and sacrifices: wherefore it is of necessity that this man have somewhat also to offer.
Heb 8:4 For if he were on earth, he should not be a priest, seeing that there are priests that offer gifts according to the law:
Heb 8:5 Who serve unto the example and shadow of heavenly things, as Moses was admonished of God when he was about to make the tabernacle: for, See, saith he, that thou make all things according to the pattern shewed to thee in the mount.
Heb 8:6 But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises.
The Old Covenant tithes were directly related to the function of the Levitical priesthood, which was merely a shadow of what Christ would do on the Cross. The tithes were only from landowners, only of crops and livestock (not money or even of fish caught in the sea), and were given from the people only to the Levites, who in turn gave the best tenth of these to the priests.
To say that New Covenant believers are required to offer tithes is indirectly to argue the following:
1. That church ministers--and not Christ--succeeds the function of the Levites and priests, which the Bible never says.
2. That tithes come from net/gross/gross+benefits monetary income--earned wages--which the Law never codified. Wage earners existed under the Old Covenant and they worked for landowners. They did not tithe of the money they earned; only the landowners tithed of the increase of the crops and livestock that they grew and raised per year.
3. That the intricate system of tithes in the Old Covenant that was
commanded is somehow irrelevant to the discussion. The Israelite landowners had to follow a seven-year cycle and a Jubilee cycle:
a. Every first, second, fourth, and fifth years, a tithe went to the Levites and another was used for the Feast of Tabernacles in Jerusalem where the tithers ate them.
b. Every third and sixth years, a tithe was laid up in community storage for the Levites and poor.
c. Every seventh year was a Sabbath year in which were no harvest gatherings and NO TITHES.
d. Every fiftieth year--the year of Jubilee--after seven of these cycles, debts were forgiven and servants were freed. There were also NO TITHES.
4. That the New Testament teaches tithing for the New Covenant, which it does not.
It all boils down to this: either we are required to tithe exactly according to the rules spelled out in the Mosaic Law, including the timing, the substance, the source, the recipient, and the action, or we are not at all. You can give 10% of your salary to a church (which is a good thing), but you simply cannot insert this action where the Bible says "tithe" and claim to be following it. Period.