1. Indentured Servants – Those who have to pay of a debt and can’t so they sell their labor.
2. Bond-slaves – Those whose debt is payed off but love their master and decide to live under him.
3. True Slaves – Those who are completely unwilling to do something but are forced through fear or manipulation.
*Christians are bond-slaves just as was Judaism in the Ancient Near East. Working at a low-income job or having to pay legal fees would probably be closer to indentured servants (hah). And the slave trade in Africa (especially the 18th century) was true slavery. The American south (18-19th cent.) bordered between indentured servants and true slaves.
Recommended Book: Justice: Rights and Wrongs by Nicholas Wolterstorff (Princeton University Press, 2008.)