And knew not until the flood came, and took them all away; so shall also the coming of the Son of man be.(Matthew 24:39)

And knew not - That is, they knew not the exact time until it came upon them. So, says he, it shall be when the Son of man shall come. They shall not know "the precise time" until he comes, and then they will be found engaged in the ordinary business of life unconcerned.

Then shall two be in the field; the one shall be taken, and the other left.(Matthew 24:40)

Then shall two be in the field ... - The calamity will come suddenly. There will be no escape for those whom it overtakes.

One shall be taken - The word "taken" may mean either to be taken away from the danger - that is, rescued, as Lot was (Luke 17:28-29)

Two women shall be grinding at the mill; the one shall be taken, and the other left.(Matthew 24:41)

The meaning of this verse is similar to the former. Of two persons sitting near each other, one shall be taken and the other. left. The calamity would be sudden, and would come upon them before they were aware.(Exodus 11:5); (Job 31:10); (Isaiah 47:2);(Judges 16:21).

24For as the lightning, that lighteneth out of the one part under heaven, shineth unto the other part under heaven; so shall also the Son of man be in his day. 25 But first must he suffer many things, and be rejected of this generation. 26And as it was in the days of Noe, so shall it be also in the days of the Son of man. 27They did eat, they drank, they married wives, they were given in marriage, until the day that Noe entered into the ark, and the flood came, and destroyed them all. 28Likewise also as it was in the days of Lot; they did eat, they drank, they bought, they sold, they planted, they builded; 29But the same day that Lot went out of Sodom it rained fire and brimstone from heaven, and destroyed them all. 30Even thus shall it be in the day when the Son of man is revealed. 31In that day, he which shall be upon the housetop, and his stuff in the house, let him not come down to take it away: and he that is in the field, let him likewise not return back. 32Remember Lot's wife. 33Whosoever shall seek to save his life shall lose it; and whosoever shall lose his life shall preserve it. 34I tell you, in that night there shall be two men in one bed; the one shall be taken, and the other shall be left. 35Two women shall be grinding together; the one shall be taken, and the other left. 36Two men shall be in the field; the one shall be taken, and the other left. 37And they answered and said unto him, Where, Lord? And he said unto them, Wheresoever the body is, thither will the eagles be gathered together.(Luke 17-24-37)

Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,(1 Corinthians 15:51)

Behold I show you - This commences the third subject of inquiry in the chapter, the question, what will become of those who are alive when the Lord Jesus shall return to raise the dead? This was an obvious inquiry, and the answer was, perhaps, supposed to be difficult. Paul answers it directly, and says that they will undergo an instantaneous change, which will make them like the dead that shall be raised.

A mystery - On the meaning of this word,(1 Corinthians 2:7)

We shall not all sleep - We Christians; grouping all together who then lived and should live afterward, for his discussion has relation to them all.

1) He is speaking of Christians as such - of the whole church that had been redeemed - of the entire mass that should enter heaven; and he groups them all together, and connects himself with them, and says, "We shall not die; we Christians, including the whole church, shall not all die," etc.

But we shall all be changed -
the sense is, that all who are alive at the coming of the Lord Jesus shall undergo such a change as to fit them for their new abode in heaven; or such as shall make them like those who shall be raised from the dead. This change will be instantaneous, for it is evident that God can as easily change the living as he can raise the dead; and as the affairs of the world will then have come to an end, there will be no necessity that those who are then alive should be removed by death; nor would it be proper that they should go down to lie any time in the grave. The ordinary laws, therefore, by which people are removed to eternity, will not operate in regard to them, and they will be removed at once to their new abode.

In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.(1 Corinthians 15:52)

In a moment - a point of time which cannot be cut or divided. A single instant; immediately. It will be done instantaneously.

In the twinkling of an eye - This is an expression also denoting the least conceivable duration of time. The suddenness of the coming of the Lord Jesus is elsewhere compared to the coming of a thief in the night; (2 Peter 3:10)

At the last trump - When the trumpet shall sound to raise the dead. The word "last" here does not imply that any trumpet shall have been before sounded at the resurrection, but is a word denoting that this is the consummation or close of things; it will end the economy of this world; it will be connected with the last state of things.

For the trumpet shall sound-
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. -( Matthew 24:31)

And the dead shall be raised -
Verily, verily, I say unto you, The hour is coming, and now is, when the dead shall hear the voice of the Son of God: and they that hear shall live.(John 5:25)

For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep. (1 Thessalonians 4:15)

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(1 Thessalonians 4:16)

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.(1 Thessalonians 4:17)

God Bless

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faith requires spiritual life - blind faith is the domain of the spiritually dead.
faith is given by God - blind faith is drummed up by the individual.
faith is based on evidences - blind faith is based on wishful thinking.
faith enables contact with God - blind faith prevents contact with God.
faith brings glory to God - blind faith dishonours God.
faith is found in the Bible - blind faith is found in religiously superstitious people.