If you'd like to set off a nice, grumpy argument in the midst of a group of preachers, teachers, and mostly learned Christians, start a discussion of tithing. You'll get some remarkable responses that range from "A Christian that does not give 10% is robbing God" to "Anyone that thinks a Christian has to give anything is a grace-denying legalist."
Why is there such diversity of opinion on this issue? For starters, and for a whole 'nother blog post, sometimes we're smarter than we need to be and spend too much effort overthinking things. However, that's not going to fit on this blog today.
Instead, let's look at the overall idea of the tithe. First, this is the fundamental definition: a "tithe" is 10% of something. It can be 10% of anything. The generic definition does not specify the recipient of the tithe. It's a principle of giving that's found inside and outside of the Bible. J.R.R. Tolkien references a "tithe of strength" in The Lord of the Rings, and other ancient treaties show that he didn't invent the idea. Kings would demand from their vassals military strength, occasionally in units of 10%.
There are a variety of religions that operate under the principle of giving of produce, cattle, or wealth in a tithe. It's typically seen, both in Scripture and out, as a tithe on increase or a tithe on firstfruits. The former is typical of animals, the latter of produce. Most ancient texts speaking of a tithe predate monetary economies, so there is actually little ancient observation of a monetary tithe.
For the Christian, this debate also strikes into the question of how much of the Old Testament doe we obey as Gentiles adopted through Christ? We certainly should all agree there are Old Testament commands that bind us: grace entitles you not to murder or steal at leisure. Other parts we know are fulfilled by and in Christ at the cross: you need not kill an animal for your sins, as Jesus was your perfect, atoning, substitute sacrifice. After all, He subs not for the sheep but for you.
There's pretty clear guidance that the dietary laws are not binding, that not marrying an ethnic Israelite is ok, and the Feasts and Fasts aren't part of our religious observance.
So we come to the tithe. If your first thought and objection to tithing is that it is only part of the Old Testament Law, you'd only be partly right. The OT Law does command the tithe. In fact, there are a couple of instances of commanded tithe, such that there were 2 annual tithes and 1 triennial tithe. So, 2 years you're up to 20% and one year 30%. When Samuel warns the people about a king, he points out that the king will likely want a tithe, too, in taxes. So it's possible monarchal Israel paid 30% some years and 40% others.
Then, the prophets, especially Malachi, highlight that a failure to tithe was causing a withholding of God's blessing on the people. Malachi 3 is the most-oft cited passage on tithing. From Malachi, we jump to the New Testament. The only explicit tithe reference is when the Lord Jesus condemns the Pharisees for tithing on their spices (probably grown in little window gardens) but oppressing the poor. He states that they were right on the tithe and wrong on the oppression, that they should have done both.
That's it. The New Testament references giving for a special offering to the needy of Jerusalem, but nothing about a continual, systematic giving system.
So, some state the tithe belongs to the law. Except we come, now, to Abram and Genesis 14. Here, Abram has been successful as he battled the forces of Chedarlaomer for the lives of Lot and the other captives. He meets Melchizedek, recorded as a "priest of God Most High" and identified in Hebrews as a type of Christ.
And Abram gives a tithe to Melchizedek as a thank offering, a freewill gift of what he has. What does he have? A combination of recovered plunder and whatever else he got in defeating Chedarlaomer. This passage puts a free gift of a tithe preceding the Law.
Nothing required Abram to make this gift. Scripture doesn't tell us why he chose that amount. There's nothing there, so arguing that he was commanded argues from silence. Arguing he did it for fun is from silence.
So, you see the source of the argument? You can't point to a Biblical verse that mandates that one absolutely must tithe. You can build a case for it---and a case against it.
So, what's my case?
Abram/Abraham is not only the father of the faith, the initial recipient of the promise, and the friend of God. He's also a good example to follow.
I see Abram responding to his success by giving, freely, a gift to God's priest of a tithe. That's 10% of what he had, given as a response to God's grace. He gives it to Melchizedek and worships God there. How does Melchizedek use it? Who knows? He doesn't build a temple or synagogue or church, he doesn't do---well, we don't know.
From this I extract and understand this as the principle: As a grace-filled response to God's provision of life, I freely give at least a tithe of what I have to the work of the Kingdom of God. Yes, there's some logic leaps in that, but that's how I see it. Typically, that gift goes to what I understand to be the center of Kingdom work in my life: the local church. Occasionally, I see cause for it to go elsewhere: missions organizations, food programs, and so forth.
I find this makes the most sense to me of the narrative. Is a tithe required? No. But it is exampled, both before the law and in the law. The silence of the New Testament regarding tithing could be as much because everyone already did it as it could be that no one did it (that's why you don't argue from silence).
The New Testament reality is recognizing God as the owner of all that I have and am. Giving 10% of what is His to the work of the Kingdom is actually a pretty easy part of that task. Spending the 90% that I keep appropriately, well, that's another matter…