Churches today teach that a 10% tithe (at a minimum) based on all income should be paid to the church (either being the representative of God on Earth or as the modern Levites).

The biggest controversy is whether it should be paid on gross income or net income.

The second biggest controversy is the right of people to pay whom they wish (ie self-supporting ministries, etc), instead of the organized central church.

By the time this study is completed these "controversies" will appear insignificant.