When a progressive tense is used in the independent clause, the dependent clause typically uses the tense.

simple past tense

Explanation:

Past tense is used.It tells us that an action which was happening in the past was interrupted by another action in the past too.

the purpose in this excerpt is that you should never do things like that because according to the bible, if you have more than one wife it's wrong and a huge sin. i hope this .

i have a basic answer but if you want a more in depth