Matthew 10:28 Do not be afraid of those who kill the body but cannot kill the soul. Instead, fear the one who is able to destroy both soul and body in hell.

Luke 12:4 “I tell you, my friends, do not be afraid of those who kill the body, and after that have nothing more they can do. 12:5 But I will warn you whom you should fear: Fear the one who, after the killing, has authority to throw you into hell. Yes, I tell you, fear him!

N.T. Wright (Jesus and the Victory of God) understands ‘those who kill the body’ to be the Romans, whereas ‘the one who can destroy both soul and body in hell’ is Satan, the real enemy.

In more detail, Wright argues:

‘Some have seen ‘the one who can cast into Gehenna’ as YHWH; but this is unrealistic. Jesus did not, to be sure, perceive Israel’s god as a kindly liberal grandfather who would never hurt a fly, let alone send anyone to Gehenna. But again and again—not least in the very next verse of this paragraph—Israel’s god is portrayed as the creator and sustainer, one who can be lovingly trusted in all circumstance, not the one who waits with a large stick to beat anyone who steps out of line. Rather, here we have a redefinition of the battle in terms of the identification of the real enemy. The one who can kill the body is the imagined enemy, Rome.  Who then is the real enemy? Surely not Israel’s own god. The real enemy is the accuser, the satan.’ (Jesus and the Victory of God, p454f)

(The first word in the above quote (‘some’) is a serious understatement.  As will be shown below, the great majority of commentators think that the reference is to God, not Satan.)

Wright adds, in a footnote to the above:

‘Perhaps this is a clue to the meaning of the closing phrase of the Lord’s Prayer: ‘deliver us from the poneros’, the Evil One (Mt. 6:13).’

(Stier is one of a small number of commentators who take the same view as Wright.)

But, as Paul R. Eddy (In Jesus and the Restoration of Israel, p47) comments:

‘Both the long-standing “fear of Yahweh” tradition and the common apocalyptic theme that pictured God, not Satan, as the judge who would finally destroy his adversaries in the eschatological flames—themes the Gospels suggest were not foreign to Jesus (e.g., Mk 9:45–47; Lk 18:1–4)—count against Wright’s interpretation.’

And France remarks, ‘No such power is attributed to Satan in the Bible, nor is the Christian bidden to fear him.’

Morris thinks that it is highly likely that God, not Satan, is meant here:

‘A few commentators have held that the one with power to cast into hell is Satan, but this should certainly be rejected. The evil one can operate only within the limitations God assigns him and there is no indication that God ever gave him this power. Moreover we are not to fear Satan but to resist him (Jas 4:7; 1 Pet. 5:9). It is God who has power over the eternal issues and Jesus repeats, yes, I tell you, fear him!’

Edwards, similarly:

‘The one who “has authority to throw you into hell” (v. 5) might seem at first to refer to Satan, but it almost certainly refers to God, for in scriptural tradition “the one who has power to cast into Gehenna is God.” Thus God is to be feared (23:40; Ps 119:120; Heb 10:31; Rev 14:7, 10), whereas Satan is not to be feared but resisted (Jas 4:7; 1 Pet 5:9).’

Keener (IVPBBCNT):

‘All Jewish hearers would understand “the one who has authority to cast into hell” as God, the judge, whose power the wise are respectfully to “fear” (e.g., Prov 1:7).’

Blomberg:

‘The NIV rightly capitalizes “One” as referring to God and not the devil (cf. Jas 4:12).’

So also, among modern commentators: Evans, Bock, Stein, Garland, Nolland, Barclay, L.T. Johnson, Schreiner (ECB), Wilcock, Geldenhuys, Hendriksen, Marshall, Liefeld (EBC), France, Mounce, Osborne, Hagner, Carson, J. Green (DJG, 2nd ed), the contributor to HSB (F.F. Bruce?) and S.E. Porter (NDBT, p497).

Bruner draws on a number of older commentators in the following:

‘Fear God or fear everything! “He who does not fear God, fears everything save him: 1 Pet 3:14–15” (Bengel, 1:161). “Let us fear therefore, that we may not fear” (Augustine, Serm., 15[65]:1:306). It is God who is to be feared in this text; we are never told to fear Satan in Scripture (McNeile, 145; Gundry, 197…). Augustine, Serm., 15(65):7:308, gives the best sense of Matt 10:28 in its context: “Fear not then, O Martyr, the sword of thy executioner; fear only thine own tongue, lest thou do execution upon thine own self, and slay, not thy body, but thy soul.” Chrysostom, C.A., 390–90, is also wise: “See how He puts above all other perils, dangers, and even above the worst [peril], death, the fear of God.… Note also that He does not hold out to them deliverance from death, but encourages them to despise it; which is a much greater thing than to be rescued from death.”’

Bruner adds:

‘People can hurt us only temporarily; the Father can sentence us permanently. The disciple will transfer fears from people to God, from what people will do to what the Father will do. And blessedly, the one who fears the Father is liberated from fear of people—no little liberation. The tender-minded message that the Father of Jesus Christ is not to be feared but loved is a pious fraud.’

Among other older commentators taking the same view: Calvin, Henry, Poole, Dickson (implied), Gill, Barnes, Ryle, JFB (implied), and Ellicott.