I believe the tribulation spoken about in the New Testament, has been happening in varying degrees, throughout history. Certain times and certain places experience more tribulation than others. For example, the Christians in the first century faced awful persecution under Nero and Domitian, then later under Trajan, Aurelius, Severus, Decius, Valerian, Maximinus, Aurelian, Diocletian and Galerius. In the middle ages, the Catholic church tortured and burned at the stake those they considered heretics. And during the reformation, persecution of men like Tyndale, Blaurock, Schlaffer and many more, demonstrates the ongoing tribulation that Christians were warned to expect. Even today, Christians are persecuted in places like China, Pakistan and many Islamic countries.
Tribulation doesn’t have to be as dramatic as persecution though. Every day life can involve tribulation. People die, people’s marriages break down, people have terrible accidents or horrific diseases etc. We read in Acts 14:21-22
When they had preached the gospel to that city and had made many disciples, they returned to Lystra and to Iconium and to Antioch, (22) strengthening the souls of the disciples, encouraging them to continue in the faith, and saying that through many tribulations we must enter the kingdom of God.
Before the return of Jesus, I think worrying things will happen. We are told in Luke 21:25-28
“And there will be signs in sun and moon and stars, and on the earth distress of nations in perplexity because of the roaring of the sea and the waves, (26) people fainting with fear and with foreboding of what is coming on the world. For the powers of the heavens will be shaken. (27) And then they will see the Son of Man coming in a cloud with power and great glory. (28) Now when these things begin to take place, straighten up and raise your heads, because your redemption is drawing near.”
The reference to the roaring of the sea and waves indicates turmoil in the nations. And Bible prophecy makes it very plain that there will be very troubled times, especially for the nation of Israel. We should concentrate on verse 28, where Jesus tells us to raise our heads because our redemption is drawing near. So the saints will not be taken out of these difficult times being referred to, although they may not be directly impacted by them.
I think life will be going on as usual for many. This in itself can be a big problem — we are lulled into a sense of security and may tend to forget God. Jesus warns us about the troubles of the last days in Luke 21:34-36
“But watch yourselves lest your hearts be weighed down with dissipation and drunkenness and cares of this life, and that day come upon you suddenly like a trap. (35) For it will come upon all who dwell on the face of the whole earth. (36) But stay awake at all times, praying that you may have strength to escape all these things that are going to take place, and to stand before the Son of Man.”
The things we need to escape: being weighed down with dissipation, drunkenness and cares of this life. Jesus also refers to this sort of thing in Matthew 24:38-39
For as in those days before the flood they were eating and drinking, marrying and giving in marriage, until the day when Noah entered the ark, (39) and they were unaware until the flood came and swept them all away, so will be the coming of the Son of Man.
In other words, we can get so caught up in the ordinary things of life, and they can mean so much to us, that the things of God are forgotten. This is probably the biggest danger we face.
Paul also warns of these dangers in 2 Timothy 3:1-5
But understand this, that in the last days there will come times of difficulty. (2) For people will be lovers of self, lovers of money, proud, arrogant, abusive, disobedient to their parents, ungrateful, unholy, (3) heartless, unappeasable, slanderous, without self-control, brutal, not loving good, (4) treacherous, reckless, swollen with conceit, lovers of pleasure rather than lovers of God, (5) having the appearance of godliness, but denying its power.
Now to comment on the rapture — I am guessing you are thinking of 1Thes 4:15-17
(15) For this we declare to you by a word from the Lord, that we who are alive, who are left until the coming of the Lord, will not precede those who have fallen asleep. (16) For the Lord himself will descend from heaven with a cry of command, with the voice of an archangel, and with the sound of the trumpet of God. And the dead in Christ will rise first. (17) Then we who are alive, who are left, will be caught up together with them in the clouds to meet the Lord in the air, and so we will always be with the Lord.
We have here the scenario of Jesus returning to the earth to establish God’s Kingdom on earth. The faithful from the beginning of time, who are sleeping the sleep of death, are resurrected, and the living faithful are gathered with them to meet Jesus as he returns to earth.
I tend to think that both groups — the recently resurrected and the living saints — are caught up into the air and descend with Jesus to earth. I think this because of the reference to the clouds. Although the clouds could just be referring to the cloud of witnesses, or the saints, as in Hebrews 12:
Heb 12:1 Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with endurance the race that is set before us,
But another way to understand this passage, is that both groups remain on the ground to meet Jesus — the air referring to the fact that those recently resurrected are now in the air, not the grave. A further reason to accept the second view, is that the angel told the disciples as they watched Jesus ascend to heaven:
Act 1:10-11 And while they were gazing into heaven as he went, behold, two men stood by them in white robes, (11) and said, “Men of Galilee, why do you stand looking into heaven? This Jesus, who was taken up from you into heaven, will come in the same way as you saw him go into heaven.”
So if Jesus comes back in the same way as he went, it could mean the faithful are standing on the mount of Olives watching as Jesus descends to earth.