Lord, they have killed - This is taken from 1-Kings 19:10. The quotation is not literally made, but the sense is preserved. This was a charge which Elijah brought against the whole nation; and the act of killing the prophets he regarded as expressive of the character of the people, or that they were universally given to wickedness. The fact was true that they had killed the prophets, etc.; 1-Kings 18:4, 1-Kings 18:13; but the inference which Elijah seems to have drawn from it, that there were no pious people in the nation, was not well founded.
And digged down - Altars, by the Law of Moses, were required to be made of earth or unhewn stones; Exodus 20:24-25. Hence, the expression to dig them down means completely to demolish or destroy them.
Thine altars - There was one great altar in the front of the tabernacle and the temple, on which the daily sacrifices of the Jews were to be made. But they were not forbidden to make altars also elsewhere; Exodus 20:25. And hence they are mentioned as existing in other places; 1-Samuel 7:17; 1-Samuel 16:2-3; 1-Kings 18:30, 1-Kings 18:32. These were the altars of which Elijah complained as having been thrown down by the Jews; an act which was regarded as expressive of signal impiety.
I am left alone - I am the only prophet which is left alive. We are told that when Jezebel cut off the prophets of the Lord, Obadiah took a hundred of them and hid them in a cave; 1-Kings 18:4. But it is not improbable that they had been discovered and put to death by Ahab. The account which Obadiah gave Elijah when he met him 1-Kings 18:13 seems to favor such a supposition.
Seek my life - That is, Ahab and Jezebel seek to kill me. This they did because he had overcome and slain the prophets of Baal; 1-Kings 19:1-2. There could scarcely be conceived a time of greater distress and declension in religion than this. It has not often happened that so many things that were disheartening have occurred to the church at the same period of time. The prophets of God were slain; but one lonely man appeared to have zeal for true religion; the nation was running to idolatry; the civil rulers were criminally wicked, and were the leaders in the universal apostasy; and all the influences of wealth and power were setting in against the true religion to destroy it. It was natural that the solitary man of God should feel disheartened and lonely in this universal guilt; and should realize that he had no power to resist this tide of crime and calamities.

Lord, they have killed thy prophets - They will not permit any person to speak unto them in thy name; and they murder those who are faithful to the commission which they have received from thee.
Digged down thine altars - They are profligate and profane beyond example, and retain not the slightest form of religion.
I am left alone - There is no prophet besides myself left, and they seek to destroy me.

Lord, they have killed thy prophets,.... By the order of Jezebel, wife of Ahab king of Israel, 1-Kings 18:4. This sin of slaying the prophets of the Lord is charged upon the Jews by Christ, Matthew 23:31, and by the apostle, 1-Thessalonians 2:15. In the text in 1-Kings 19:14, it is added, "with the sword": which expresses the manner of death they were put to; and this clause is there put after the following, according to a rule of transposition among the Jews; See Gill on Matthew 27:10.
And digged down thine altars; either the altars which the patriarchs had formerly built, and were still in being; and though not used, yet were kept and had in great veneration; wherefore the pulling of them down was done in contempt of them, and of the worship of God, which had been formerly performed there; or else such altars, which the religious among the ten tribes built, since the times of Jeroboam, who forbad them to go up to Jerusalem, but ordered them to go to Daniel or Bethel; which they not choosing to do erected altars in different places for divine service, and which the Jews (r) say were allowed; for from that time, the prohibition of altars at other places than at Jerusalem ceased:
and I am left alone: meaning either as a prophet, not knowing that Obadiah had hid an hundred prophets by fifty in a cave, 1-Kings 18:4; or else as a worshipper of the true God, imagining that he was the only person in Israel, that had a true zeal for the Lord of hosts:
and they seek my life; lay in wait for it, Jezebel by her emissaries being in quest of him; it is added in 1-Kings 19:14, "to take it away"; for she had swore by her gods, that by the morrow about that time, his life should be as the life of one of the prophets of Baal he had slain; and in one copy it is added here.
(r) Kimchi in 1 Kings xviii. 30.

and I am left alone--"I only am left."

1-Kings 19:10.