Why does Paul (see 2 Thess. 2: 2–8) identify the day of the Lord with the period of time just before the Lord’s appearing, while Peter (see 2 Pet. 3: 10–12) identifies it with the destruction of the present heavens and earth over a thousand years later?

The answer involves an understanding of the meaning of the expression “the day of the Lord”. It comes from the OT as “the day of Jehovah” and is found only in the prophets from Is. 2: 12 to Mal. 4: 5.

   The prophets often prophesied of events that would take place within their lifetime or just beyond it. When these had identical features to events belonging to the “end of times” (1 Pet. 1: 20), the Holy Spirit guided the prophet to move seamlessly from the one to the other. The prophetic expression “the day of Jehovah” is used in the OT for events in both the near and the distant future. For example, Isaiah 13 is “The burden of Babylon” (v1), the kingdom that was eventually overrun by the Medes (see v17) where the word is “Howl, for the day of Jehovah is at hand” (v6). But in v9, where the expression “the day of Jehovah” is repeated, we are taken beyond the immediate future to a time when the physical heavens will be disrupted (see v10, and compare with Matt. 24: 29 and Rev. 6: 12, 13) and God says “I will punish the world for evil …” (v11).

   Throughout the OT “the day of Jehovah” is always used to describe God’s direct intervention in governmental judgement, both in the immediate and the distant future. It is a day of divine wrath and destruction. This is clear from its first occurrence in Is. 2: 12, the beginning of a section in which the detail of v19 is virtually repeated in Rev. 6: 15 and ends with the words “In that day men shall …go into the clefts of the rocks … from before the terror of Jehovah, and from the glory of his majesty, when he shall arise to terrify the earth” (v20, 21). In keeping with this dual nature of prophecy, God’s future direct judgment on earth also often involves the shaking of the heavens (see Is. 13: 10, 13; Joel 2: 10, 11; 3: 14, 15; Hag. 2: 6; Rev. 6: 12, 13) being a prophetic foretaste of God’s final judicial act in government when the present heavens and earth will be destroyed. Indeed, Isaiah was taken on to that time for we read “And all the host of the heavens shall be dissolved, and the heavens shall be rolled together as a scroll; and all their host shall fade away, as a leaf fadeth from off the vine, and as the withered [fruit] from the fig tree. … For it is the day of Jehovah’s vengeance” (Is. 34: 4, 8; see also Is. 51: 6). Thus the phrase “the day of Jehovah” is not limited to a particular period of time but is expressive of those occasions when God exerts His authority in direct governmental judgement.

   Turning to the NT, “the day of the Lord” is first used by Peter quoting Joel 2: 28–32 in Acts 2: 17–21 on the day of Pentecost. This occasion was not the fulfilment of the prophecy but the conditions then present fell within the description of the prophecy for Israel had just crucified her Messiah warranting divine judgement. In 1 Cor. 1: 8 Paul speaks of “the day of our Lord Jesus Christ” and in 1 Cor. 5: 5 and 2 Cor. 1: 14 of “the day of the Lord Jesus”. These similar, but not identical expressions, are not the equivalent of “the day of Jehovah” in the OT, for in each case the context is clearly the millennial reign of Christ—a time that “the day of Jehovah” is never used to describe.

   The day of the Lord does not belong to the present time (see 2 Thess 2: 2) for the Church has nothing to do with “the times and the seasons” (1 Thess. 5: 1) for these belong to Israel, the earth  and men in general. But when the Church has gone, the heavens will no longer be silent and God’s judgements on earth will resume, culminating in the return of the Lord in glory (see 2 Thess 2: 8). It is to this time that Paul applies “the day of the Lord” (v2). 

   Finally, to Peter, whose epistles have as background the governmental ways of God. There were mockers then, as now, who challenged the return of the Lord, failed to see any past divine intervention in judgement and claimed that “all things remain thus from [the] beginning of [the] creation” (2 Pet. 3: 4). This leads the apostle  to go on to the very end of this creation, bypassing the pre–millennial judgements and the reign of Christ, and to speak of the dissolution of the physical universe by fire. In doing so, he uses virtually the same words as Paul: “the day of [the] Lord will come as a thief” (2 Pet. 3: 10; see 1 Thess. 5: 2)—for while the event is different, it is the final act of the ‘day’ of judgment. In keeping with this setting, Peter exhorts the believers to wait for “the coming of the day of God” (v12), when there will be “new heavens and a new earth, wherein dwells righteousness” (v13). This is the day when “the Son also himself shall be placed in subjection to him who shall put all things in subjection to him, that God may be all in all” (1 Cor. 15: 28).