The idea that God’s temple and sacrificial system are now obsolete is generally accepted as fact: Christians take it for granted that Christ fulfilled the types and shadows of what we now call Ceremonial Law when He died and rose again. Any interest in observing these laws today is considered barbaric, an insult to the finished work of Christ. As far as we know, not a single Christian theologian in all recorded history believed otherwise.
This is in spite of the fact that Christ Himself says in no uncertain terms that not even the smallest detail of the Tanakh (the Old Testament), including the Levitical priesthood and the temple administration, will become obsolete or irrelevant so long as Heaven and Earth stand, not until every single prophetic word and symbol has been fulfilled. (Mt 5:17-19) In explicitly calling out this kind of error from the very start of His ministry, it is difficult to imagine how He might have presented this more clearly, openly or emphatically.
How exactly is it that the work of Christ makes the sacrificial system obsolete? Animal sacrifices never did take away sin (He 10:4); rather, they serve as a shadow of good things to come. (He 10:1, Co 2:16-17)
Why wouldn’t an elaborate and vivid illustration of the atoning work of Christ continue to help us understand and appreciate what Christ has done for us long after He accomplishes His work? (1Co 5:7-8) As it pointed forward to what Christ would do (Jn 1:29), why wouldn’t it also point backwards to what He has already done and help us to continually appreciate it? (1Co 15:23)
If we can see how an active sacrificial system might be helpful, it should be easier to see scripture describing a functional priesthood, recognized by God after the Cross. The verb tenses used are in the present tense (He 8:4-5), indicating the Levitical priesthood remains potentially functional today in God’s ecomony. (He 10:11)
We might presume this is merely an academic discussion since the temple system is presently dormant, as prophesied late in the apostolic era (He 8:13); even if we wanted to offer a sacrifice, there isn’t a legitimate way to do so. However, the mindset behind the reasoning is what is significant: do we recognize the import of Christs’ words in the Sermon on the Mount, and the beauty in what God has designed? Or are we quick to wave our hands and relegate the temple system to the history books?
When the 3rd temple is built and the holy offerings and sacrifices resume (2Th 2:3-4), this dimension of God’s law won’t be as easy to dismiss. God will be identifying Himself with this temple (Re 11:1-2), and so should we.