Of course, "apostasia" can mean a departure from the faith, but the writer would have to add "from the faith" for that meaning is not included in "aopostasia." All that is included is a departure. From what must be derived from the context or by adding words.
For example, in Acts 21:21 - And they are informed of thee, that thou teachest all the Jews which are among the Gentiles to
forsake G646 Moses, saying that they ought not to circumcise
their children, neither to walk after the customs - the writer had to add "Moses" so the reader would know what was being departed from.
You say Paul did not identify the restrainer. No, you are mistaken!
verse 6:
New International Version
And now you know what is holding him back, so that he may be revealed at the proper time.
Paul wrote that they would now know who the restrainer is. But this just goes right over most reader's heads. HOW would they now know? It is very simple: Paul JUST TOLD THEM, but wrote this so they were read again very carefully to see who this restrainer is.
Any beginning reader can understand verses 7 & 8: there is a force that is restraining, preventing the man of sin from being revealed until the right time, but that restrainer WILL BE TAKEN OUT OF THE WAY. And THEN the man of sin will be revealed.
Got it? The restrainer is preventing the revealing, but when the restrainer is taken out of the way, THEN the man of sin will be revealed.
verse 3:....the man of lawlessness is revealed, the man doomed to destruction. He will oppose and will exalt himself over everything that is called God or is worshiped, so that he sets himself up in God's temple, proclaiming himself to be God.
Note carefully what we read here in the NIV: the man of lawlessness
IS REVEALED. Then Paul tells us what he will do once he IS REVEALED.
But wait! He cannot be revealed until the one restraining is "taken out of the way!" Paul is telling us that in verse 3a the one restraining IS taken out of the way! It is the church, who will be taken out of the way. And apostasia can certainly mean a spacial depature, where from a whole, a part is taken and moved to a different location.
Here is what STrong's wrote for "APO" Greek, which is the first part of Apostasia:
B. of separation of a part from the whole
i. Where of a whole some part is taken
C. of any kind of separation of one thing from another by which the union or fellowship of the two is destroyed
D. of a state of separation, that is of distance
i. physical, of distance of place
ii. temporal, of distance of time
Please answer this question:
when the rapture takes place, with the church "depart?"
Will the church be "separated" by physical distance from earth?
Will their "union" with earth be destroyed?
Of course you know the answer to all these is YES.
So Paul's meaning for apostasia is the one restraining being "taken out of the way." It is THE (again significant) Departing of the church, which will remove the restraining force.
So paul wrote, "and NOW YOU KNOW!"
