“But woe/alas to you, scribes and Pharisees, hypocrites! because you shut the kingly rule of heaven against men, for you do not enter in yourselves, nor do you allow those who are entering in to enter.”
In Matthew 12:28 Jesus had castigated them for not seeing that the Kingly Rule of God had ‘come upon' them. Here He follows that up by charging them with also preventing others from entering under that Kingly Rule because of their own blindness and obstinacy. They not only do not enter in, but they carefully lock the door in order to prevent others entering in, by means of their persuasive words and clever manipulation of Scripture. As the next verse makes clear it particularly angered Him that they put off seekers after truth from finding that truth, (and thus prevented the Shepherd finding His sheep). No wonder He was ‘angry'.
The word ‘hypocrites', already used by Him of people like this who could not see beyond their noses and rejected every sign given to them (Matthew 16:3; Matthew 22:18), and of those who did everything for their own glory (Matthew 6:1-18) will now be applied to them continually. They made a great show of godliness, and yet stood in the way of those who would become truly godly.
‘You do not enter in.' The natural meaning of this is that it expresses their failure to enter under the Kingly Rule of Heaven at that very time. In other words they had failed to respond to the word of the Kingly Rule and become true ‘sons of the Kingly Rule' (Matthew 13:19; Matthew 13:38), even though they had originally been in line for such a privilege (Matthew 8:12). God had therefore had to remove them and replace them with others (compare Matthew 21:41-43).
‘Shut (lock) the Kingly Rule of Heaven against men.' The verb kleio is connected with the noun for ‘key' (kleis) and signifies the same idea as the modern equivalent of ‘bolting the door' in order to prevent entry. Paradoxically they used their keys of knowledge in order to prevent men from entering the Kingly Rule of Heaven - compare Luke 11:52. (Which was why those keys would have to be taken out of their hands and put into the possession of the Apostles - Matthew 16:18). They had made every effort to interfere with peoples' interest in what John and Jesus had had to say by the restrictions that they put on people in the name of God, and by exerting their religious authority. No doubt many who had heard Jesus had consulted with the Scribes and Pharisees and had had cold water poured by them on their new found enthusiasm.
Note how in Matthew 5:3 the poor in spirit receive the Kingly Rule of Heaven, while here the hypocrites do not enter it or allow others to enter.