Here the words »Yet again, once for all« denote the removal of the things which can be shaken –created things– in order that the things which cannot be shaken may remain.
It said, »Write forthwith in a roll an account of what you see, and send it to the seven Churches–to Ephesus, Smyrna, Pergamum, Thyateira, Sardis, Philadelphia and Laodicea.«
And he said to me, »Write as follows: `Blessed are those who receive an invitation to the Marriage Supper of the Lamb.'« And he added, still addressing me, »These are truly the words of God.«
and that if any one takes away from the words of the book of this prophecy, God will take from him his share in the Tree of Life and in the holy city–the things described in this book.
And he said to me, »These words are trustworthy and true; and the Lord, the God of the spirits of the Prophets, sent His angel to make known to His servants the things which must soon happen.