Tithing
Whether the tithe binds the church, or whether giving is free and cheerful.
Malachi 3:8-12
8Will a man rob God? Yet you rob me! But you say, ‘How have we robbed you?’ In tithes and offerings.
9You are cursed with the curse; for you rob me, even this whole nation.
10Bring the whole tithe into the storehouse, that there may be food in my house, and test me now in this,” says Yahweh of Armies, “if I will not open you the windows of heaven, and pour you out a blessing, that there will not be room enough for.
11I will rebuke the devourer for your sakes, and he shall not destroy the fruits of your ground; neither shall your vine cast its fruit before its time in the field,” says Yahweh of Armies.
12“All nations shall call you blessed, for you will be a delightful land,” says Yahweh of Armies.
2 Corinthians 9:6-7
6Remember this: he who sows sparingly will also reap sparingly. He who sows bountifully will also reap bountifully.
7Let each man give according as he has determined in his heart, not grudgingly or under compulsion, for God loves a cheerful giver.
What each tradition says
Rabbinic / Midrashic
Jacobs, Seligsohn, and Bacher write that the Mosaic law later made the tithe obligatory upon the Israelites. The tithe, whether of the seed of the land or of the fruit of the tree, belonged to Yhwh and consequently was holy.
Joseph Jacobs, M. Seligsohn, Wilhelm Bacher, Tithe (The Jewish Encyclopedia, New York: Funk & Wagnalls, 1901-1906) — Section 'Biblical Data'
Patristic
Irenaeus says the Jews had tithes of their goods consecrated to God. Those who have received liberty set aside all their possessions for the Lord's purposes, giving joyfully and freely, not the less valuable portions of their property, since they hope for better things. The poor widow who cast all her living into God's treasury acted this way.
Irenaeus of Lyons, Against Heresies, Book IV, in Ante-Nicene Fathers, vol. 1 (eds. A. Roberts and J. Donaldson) — Book IV, ch. 18, §2
Catholic
Aquinas holds that man's obligation to pay tithes arises partly from natural law and partly from the institution of the Church. The Church, considering the requirements of time and persons, might ordain the payment of some other proportion.
Thomas Aquinas, Summa Theologiae (Fathers of the English Dominican Province trans., second and revised edition) — II-II, q. 87, a. 1 ('Whether men are bound to pay tithes under a necessity of precept?'), respondeo
Orthodox
The Constitutions of the Holy Apostles teaches that, as was said formerly, oblations and tithes belong to Christ our High Priest and to those who minister to Him. It calls readers to hear this teaching attentively.
Anonymous (Constitutions of the Holy Apostles), Constitutions of the Holy Apostles, in Ante-Nicene Fathers, vol. 7 (eds. A. Roberts and J. Donaldson) — Book II, Sec. IV, ch. XXV ('Of First-Fruits and Tithes, and After What Manner the Bishop is Himself to Partake of Them, or to Distribute Them to Others')
Reformed / Protestant
Calvin says Paul wanted the Corinthians to give largely so the brethren would be more abundantly aided, but he did not want to extract anything from them against their will. Instead, Paul exhorts them to give willingly whatever they are prepared to give.
John Calvin, Commentaries on the Second Epistle of Paul the Apostle to the Corinthians (trans. John Pringle; Calvin Translation Society; Christian Classics Ethereal Library) — Commentary on 2 Corinthians 9:7
Evangelical
Albert Barnes says the main point of 2 Corinthians 9:7 is that giving should be voluntary and cheerful. It should not be forced by others’ pleas or given only from urgent need. Instead, it should be an offering of the heart.
Albert Barnes, Albert Barnes' Bible Commentary — On 2 Corinthians 9:7