When Republican presidential hopeful Mitt Romney released his federal tax returns for the past two years, he disclosed that he and his wife, Ann, gave about 10 percent of their income to their church, a well-known religious practice called tithing.
In that way, the Romneys are typical Mormons, members of a church that is exceptionally serious about the Old Testament mandate to give away one-tenth of one's income.
But compared to other religious Americans, the Romneys and other Mormons are fairly atypical when it comes to passing the plate. Across the rest of the religious landscape, tithing is often preached but rarely realized.
Research into church donations shows a wide range of giving, with Mormons among the most generous relative to income, followed by conservative Christians, mainline Protestants and Catholics last.
Over the past 34 years, Americans' generosity to all churches has been in steady decline, in good times and in bad, said Sylvia Ronsvalle, whose Illinois-based Empty Tomb Inc. tracks donations to Protestant churches.
Ronsvalle's research shows that since 1968, contributions have slowly slumped from 3.11 percent of income to 2.38 percent, despite gains in prosperity.
In her view, churches have failed "to call people to invest in a much larger vision." She believes that explains why giving to missions, distant anti-poverty programs or faraway ministries has sunk faster than giving for the needs of local congregations.