God is perfect and would not command us to do that which is immoral. God commanded the OT Jews to marry multiple women (The Levirite marriage). Therefore, this Levirite arrangement was not sin. This means that polygamy is not per se (innately) sinful in all circumstances, or else God could not have commanded it to be done. Just as not all killing is murder, not all polygamy is sinful polygamy. Therefore, polygamy is not sinful in and of itself. ---Does this argument check out? If sombody gave you this argument stating that polygamy was not sin, how would you respond?