Because the verse you posted, 16, says:
Do you not know that if you YIELDED yourselves to any one as obedient slaves, you are slaves of the one whom you obey...
Yield, in this case, means to give way to a force. It's a voluntary action.
yield
/jiːld/
verb
- 1.
produce or provide (a natural, agricultural, or industrial product).
"the land yields grapes and tobacco"
- 2.
give way to arguments, demands, or pressure.
"the Western powers now yielded when they should have resisted"
sinonimi: surrender, capitulate, submit, relent, admit defeat, accept defeat, concede defeat, back down, climb down, quit, give in, give up the struggle, lay down one's arms, raise/show the white flag, knuckle under
Slaves don't choose. Slaves obey their master.