The question posed here came in response to the advocates of tithing and proportionate giving. Among the first to voice this question was Catharine E. Beecher, a female educator and writer on “domestic” issues in mid-nineteenth century America. In her popular work, Treatise on Domestic Economy, she offered a deft analysis of the hazards of claiming that any of us know for sure what and how much others should give. Beecher may have had in mind the perrorations of Lyman Beecher, her father and a well-known champion of various evangelical causes. (See Resource 4.2 - Lyman Beecher, Capital Enough to Evangelize the World)

In any event, her reflections are very much worth studying. Read Resource 4.4 -  Catharine E. Beecher, No Duty More Difficult to Fix by Rule.

The varieties of styles of giving is also explored in Elizabeth M. Lynn and D. Susan Wisely, “Toward a Fourth Philanthropic Response: American Philanthropy and Its Public” (The Perfect Gift) pp. 102-118.

Another source of wisdom on this topic is a book that unhappily is no longer available, except in larger libraries: Luke T. Johnson, Sharing Possessions: Mandate and Symbol of Faith (Philadelphia: Fortress Press, 1981).

In writing about “the significance of possessions for the Christian life.” Johnson declared, “It is terribly difficult, I think, for the Christian who takes the Bible seriously and regards it as providing guidance for daily life, to find a clear-cut concrete directive which can be followed consistently. To be a real Christian, must I be poor, join a commune, or make enough money to give alms(p. 25.)?"  Johnson ruefully concluded his reflections by noting that “if there is one thing many of us would secretly like to get out of the Scriptures, it is a rule book(p.25)." In this connection, read Puzzles 1.4 - Is There a Rule of Giving that Fits Most Circumstances?