John Gill Bible Commentary

A fire goeth before him, Not the fiery law, which went forth from his right hand on Mount Sinai; but rather his Gospel, which, as it enlightens, warms, comforts, and refreshes his people, searches, torments, and destroys his enemies, and is the savour of death unto death to them; see Jer 23:29. Some apply this to the gifts of the Spirit on the day of Pentecost, signified by cloven tongues of fire; but then no such effect followed as mentioned in the next clause: it seems best to interpret it of his wrath, which, like fire, was poured out to the uttermost on the Jews, for their disbelief and rejection of him; they would not have him to reign over them; they despised his Gospel, and slew his servants; wherefore he sent the Roman armies to them, who destroyed those murderers, and burnt their city, Mat 22:7, this will be also verified in the second coming of Christ, who will descend in flaming fire, and the earth will be burnt up, and all that is therein, Th2 1:7, some Jewish writers interpret this of the war of Gog and Magog, in Ezekiel, which they suppose still future; as, when it is, fire will be sent and rained upon them, Eze 38:22, but may be better applied to the Gog and Magog in Rev 20:8. and burneth up his enemies round about; so that none can escape: this was true of the Jewish nation, who were burnt up; so that there was not left root nor branch in it, Mal 4:1, and will be true of the wicked, at the general conflagration of the world, upon Christ's second coming; and of the Gog and Magog army, after the resurrection.