“The Day of the Lord - as a thief in the night”

A thief doesn’t announce when he intends to arrive.

The Apostle Peter, writing to believers in Christ, describes the Day of the Lord.

“l now write unto you; in both which I stir up your pure minds by way of remembrance: that ye may be mindful of the words which were spoken before by the holy prophets, and of the commandment of us the apostles of the Lord and Saviour: knowing this first, that there shall come in the last days scoffers, walking after their own lusts, and saying, Where is the promise of his coming? for since the fathers fell asleep, all things continue as they were from the beginning of the creation.

For this they willingly are ignorant of, that by the word of God the heavens were of old, and the earth standing out of the water and in the water: whereby the world that then was, being overflowed with water, perished: but the heavens and the earth, which are now, by the same word are kept in store, reserved unto fire against the day of judgment and perdition of ungodly men.

But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day. The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.

But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up. Seeing then that all these things shall be dissolved, what manner of persons ought ye to be in all holy conversation and godliness, looking for and hasting unto the coming of the day of God, wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat? Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness.

Wherefore, beloved, seeing that ye look for such things, be diligent that ye may be found of him in peace, without spot, and blameless. And account that the longsuffering of our Lord is salvation; even as our beloved brother Paul also according to the wisdom given unto him hath written unto you; as also in all his epistles, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as they do also the other scriptures, unto their own destruction.”
II Peter 3:1-12

The Apostle Paul, when writing to believers in Thessalonica said…

“For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.“
I Thessalonians 4:16-17

“…of the times and the seasons, brethren, ye have no need that I write unto you. For yourselves know perfectly that the day of the Lord so cometh as a thief in the night.
For when they shall say, Peace and safety; then sudden destruction cometh upon them, as travail upon a woman with child; and they shall not escape.
But ye, brethren, are not in darkness, that that day should overtake you as a thief.
Ye are all the children of light, and the children of the day: we are not of the night, nor of darkness. Therefore let us not sleep, as do others; but let us watch and be sober.”
I Thessalonians 5:1-6

Conclusion
The Day of the Lord is His “appearing” (revelation) when the Lord will come as “a thief in the night” in fiery judgment.

“Behold, I come as a thief. Blessed is he that watcheth, and keepeth his garments, lest he walk naked, and they see his shame.” Revelation 16:15

False Teachings
There are many erroneous teachings abroad devised to deceive believers from walking in holiness and being in readiness for the Day of the Lord. The theory of Dispensationalism is probably the most dangerous of these deceptions; this theory, devised by J.N. Darby was later propagated by C.I. Scofield through his “Reference Bible”. Another deception was Darby’s theory of a “secret rapture”, which he devised in order to validate his “Israel and the Church” theory.

Compare Matthew 24

“For as the lightning cometh out of the east, and shineth even unto the west; so shall also the coming of the Son of man be.”

“…then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory. And he shall send his angels with a great sound of a trumpet, and they shall gather together his elect from the four winds, from one end of heaven to the other.”

“Heaven and earth shall pass away, but my words shall not pass away.”

“…of that day and hour knoweth no man, no, not the angels of heaven, but my Father only.”

“But as the days of Noe were, so shall also the coming of the Son of man be. For as in the days that were before the flood they were eating and drinking, marrying and giving in marriage, until the day that Noe entered into the ark, and knew not until the flood came, and took them all away; so shall also the coming of the Son of man be.”

“Watch therefore: for ye know not what hour your Lord doth come.”

“But know this, that if the goodman of the house had known in what watch the thief would come, he would have watched, and would not have suffered his house to be broken up.”

“Therefore be ye also ready: for in such an hour as ye think not the Son of man cometh.”