If a man abide not in me, he is cast forth as a branch... — The thought passes from the fruitful to the sterile branch, from the man who abideth to the man who will not abide in Christ. In the natural vineyard such a branch was cast forth, and then withered, and was gathered with others into bundles, and burned. The vivid picture illustrates the fearful history of a man who willeth not to abide in Christ.
And they are burned. — Better, and they burn. The tenses of this verse should be carefully observed. The burning of the withered branches of the natural vine suggests the final judgment, and the whole is thought of from that time. Hence the earlier verbs are in the past, and the later in the present tense.