Apocalypse Explained # 530
530. Saying with a great voice, signifies manifestation. This is evident from the signification of "saying with a great voice," as being manifestation, here respecting the coming state of the church near its end, which is foretold in what follows. It is said "a great voice" because it has reference to the Lord and to the universal heaven (as has been said just above).
Matthew 23:13
13
But woe unto you, scribes and Pharisees, hypocrites! for ye shut up the kingdom of heaven against men: for ye neither go in yourselves, neither suffer ye them that are entering to go in.