I have a couple more postings on tithing left in me. It may seem like I am labouring the subject, but I'm just being thorough.
You see, I think sometimes, we can take things for granted, and assume others see things the way we do. We can ask questions like "Do you tithe?", and just take for granted that "What do you tithe?" and "To whom do you bring your tithe?" are obvious.
For me these questions were not obvious. Not at first anyway. I became convicted by the Spirit of my need to tithe before I had received any thorough teaching on the subject, and I was not sure what I should tithe or to whom I should bring it.
I knew that I should tithe "my income" and that I should give it "to God", but very inconveniently God does not have a bank account, and does not accept standing orders or direct debits. Also for people who are taxed at source, there is a question about net and gross; do I tithe everything that comes into my account, or a tenth of what I get on paper?
It is here that the pre-law instances on tithing are very helpful. Abraham gave Melchizadek "a tenth of everything". And Jacob swore to give God "a full tenth of all that you give me."
This takes the whole argument away from petty details like whether it is just "agricultural products" that God is interested in. It's a question of "What has God given me?" If we recognise God as our source, then we acknowledge that all our financial provision comes from him, whether it comes, in the natural, from our employer, as a gift, in return for a service rendered, or wherever else. All that we are and all that we have is a gift from him. To give him the "full tithe" is indeed to give him a tithe of "everything". Since the taxman takes his percentage out of what we have earned, it is natural and only right that we give to God from the full amount before the taxman, whether this is done at source or not.
On one level this answer is as simple as it first appears. The tithe belongs to God, and we always bring it to God. Note that in the Old Testament, the Levites collected the tithe. It was not given to them. Not directly by the tithers anyway. The tithe was given to God, and then God gave to the Levites out of the tithe. This may seem like a subtle distinction, but it is important.
You see, in politics a phrase we hear over and over is "taxpayers money". The government of a country is responsible to the people it represents to spend the money collected wisely. There is a sense among the people of "Hey, that's our money you're spending!" But one thing we never see in the scriptures is the sense of "tithe-payers money!" The people did not give their money to the Levites, and the Levites did not get their income from the people. The people brought their tithes to God, and God gave the exclusive right to the Levites to use the money from the collected tithes. Once the people had brought their tithe, their responsibility ended, whether the money was spent by the Levites wisely or foolishly, they had faithfully brought it to God. Equally the Levites were payed from the tithe by God, and thus it was before God that they were responsible as to how they used the money. (Which is the same as everyone else once you have realised who your true source is!)
So the real question is "Who has the right to be payed by God from the tithe today?" We don't have Levites, but what were the Levites? They were people set apart by God to serve him and minister to his people, who had no other source of income. We certainly have men like this today. We should bring our tithes to God at the place where we receive ministry from those who have been set apart for this work and who have pastoral care and spiritual authority over us. It is they who have the right to take from the tithe, as a payment not from man but from God.