The children of the kingdom - That is, the children, or the people, who “expected the kingdom,” or to whom it properly belonged; or, in other words, the Jews. they supposed themselves to be the special favorites of heaven. They thought that the Messiah would enlarge their nation and spread the triumphs of their kingdom. They called themselves, therefore, the children or the members of the kingdom of God, to the exclusion of the Gentiles. Our Saviour used the manner of speech to which they were accustomed, and said that “many of the pagans would be saved, and many Jews lost.
Shall be cast out into outer darkness ... - This is an image of future punishment. It is not improbable that the image was taken from Roman dungeons or prisons. They were commonly constructed under ground. They were shut out from the light of the sun. They were, of course, damp, dark, and unhealthy, and probably most filthy. Masters were in the habit of constructing such prisons for their slaves, where the unhappy prisoner, without light, or company, or comfort, spent his days and nights in weeping from grief, and in vainly gnashing his teeth from indignation. The image expresses the fact that the wicked who are lost will be shut out from the light of heaven, and from peace, and joy, and hope; will weep in hopeless grief, and will gnash their teeth in indignation against God, and complain against his justice. What a striking image of future woe! Go to a damp, dark, solitary, and squalid dungeon; see a miserable and enraged victim; add to his sufferings the idea of eternity, and then remember that this, after all, is but an image, a faint image, of hell! Compare the notes at Mat_22:13.