1 Thessalonians 5:2

For yourselves know perfectly that the day of the Lord so cometh as a thief in the night.

Know perfectly .... "There had been no special revelation to any of the Thessalonians regarding this; they had not had the privilege of hearing Christ personally while he was upon earth; and, therefore, it may be assumed that Paul here meant that he and Silas and Timothy had fully and carefully instructed them on these things at the time of their conversion.

Day of the Lord so cometh ... "In the Greek, there is no definite article before either `day' or `Lord,' indicating that the expression was stereotyped, having become somewhat as a proper noun."[4] The expression was used extensively in the Old Testament; and Barclay summarized the Old Testament meaning of the expression thus:

(i) It would come suddenly and unexpected, (ii) it would involve a cosmic upheaval in which the universe would be shaken to its very foundations, and (iii) it would be a time when God would bring judgment upon the nations.[5]

The adoption, from the very beginning of Christianity, of this same expression, used in the sense of the day of Jesus Christ, shows how universally the early church accepted Jesus as co-equal with God. Thus, as Gloag put it, "The day of the Lord here means not the destruction of Jerusalem, nor the day of one's death, but the day of the Lord's advent."[6]

The suddenness and unexpectedness of that day were always associated with the prophecies pertaining to it. Lipscomb has a wonderful comment on this thus:

No truth seems to have been more clearly and fully taught than that the Son of man would come when not looked for by the world. Yet there is no scriptural question upon which men bestow more attention, and no question that they seek more earnestly to determine. The time has often been set, and as often proved a mistake.

Only by a righteous and pure life can one be ready for his coming. We should not only be ready for him, but should love his appearing and desire earnestly the day of his coming.[7]

[4] Raymond C. Kelcy, op. cit., p. 105.

[5] William Barclay, The Letters to the Philippians, Colossians, and Thessalonians (Philadelphia: The Westminster Press, 1975), p. 205.

[6] P. J. Gloag, op. cit., p. 102.

[7] David Lipscomb, Commentary on 1Thessalonians (Nashville: The Gospel Advocate Company, 1976), p. 63.