Matthew 18:18 Verily I say to you, Whatever things ye may bind upon the earth shall be having been bound in the heavens, and whatever things ye may loose on the earth shall be having been loosed in the heavens.
Matthew 16:19 I will give you the keys of the kingdom of heaven; and whatever you bind on earth shall have been bound in heaven, and whatever you loose on earth shall have been loosed in heaven.It is future, anticipating some act of forbidding or permitting (binding/loosing). But as the act occurs in the future, the perfect indicates that the binding or loosing was already accomplished in the past, previous to the future act. The passive simply indicates the thing being bound or loosed is the passive recipient of the action.