And what concord - (συμφώνησις sumphōnēsis). Sympathy, unison. This word refers properly to the unison or harmony produced by musical instruments, where there is a chord. What accordance, what unison is there; what strings are there which being struck will produce a chord or harmony? The idea is, then, there is as much that is discordant between Christ and Belial as there is between instruments of music that produce only discordant and jarring sounds.
Hath Christ - What is there in common between Christ and Belial, implying that Christians are governed by the principles, and that they follow the example of Christ.
Belial - Βελίαλ Belial or Βελίαρ Beliar, as as it is found in some of the late editions. The form Beliar is Syriac. The Hebrew word בּליּצל beliya‛al means literally without profit; worthlessness; wickedness. It is here evidently applied to Satan. The Syriac translates it “Satan.” The idea is, that the persons to whom Paul referred, the pagan, wicked, unbelieving world, were governed by the principles of Satan, and were “taken captive by him at his will” (2 Timothy 2:26 compare John 8:44), and that Christians should be separate from the wicked world, as Christ was separate from all the feelings, purposes, and plans of Satan. He had no participation in them; he formed no union with them; and so it should be with the followers of the one in relation to the followers of the other.
Or what part - (μερὶς meris). Portion, share, participation, fellowship. This word refers usually to a division of an estate; Luke 10:42; Acts 8:21 note; Colossians 1:12 note. There is no participation; nothing in common.
He that believeth - A Christian; a man the characteristic of whom it is that he believes on the Lord Jesus.
With an infidel - A man who does not believe - whether a pagan idolater, a profane man, a scoffer, a philosopher, a man of science, a moral man, or a son or daughter of gaiety. The idea is, that on the subject of religion there is no union; nothing in common; no participation. They are governed by different principles; have different feelings; are looking to different rewards; and are tending to a different destiny. The believer, therefore, should not select his partner in life and his chosen companions and friends from this class, but from those with whom he has sympathy, and with whom he has common feelings and hopes.