because we are at the end of days.

but how we know we are in the last days?

taken from watchtower.org :

World Wars

Jesus foretold that 'nation would rise against nation and kingdom against kingdom.' (Matthew 24:7)
In 1914 the world became involved in a war that saw the mobilizing of
nations and kingdoms in a way that was different from any war before
it. In recognition of that fact, historians at the time called it the
Great War. It was the first war of its kind in history, the first world
war. Some 20,000,000 soldiers and civilians lost their lives, far more
than in any previous war.

World War I marked the beginning of the last days. Jesus said that
this and other events would be "a beginning of pangs of distress." (Matthew 24:8)
That proved true, as World War II was even more deadly, some 50,000,000
soldiers and civilians losing their lives. In this 20th century, well
over 100,000,000 people have been killed in wars, more than four times
as many as in the previous 400 years put together! What an enormous
condemnation of human rule!

Other Evidences

Jesus included other features that would accompany the last days:
"There will be great earthquakes, and in one place after another
pestilences [disease epidemics] and food shortages." (Luke 21:11) That well fits events since 1914, as there has been a huge increase in the distresses from such calamities.

Major earthquakes are regular occurrences, taking many lives. The
Spanish influenza alone killed about 20,000,000 people following World
War I—some estimates being 30,000,000 or more. AIDS has taken hundreds
of thousands of lives and could take millions more in the near future.
Each year millions of people die of heart ailments, cancer, and other
diseases. Millions more die the slow death of hunger. Without a doubt
the 'horsemen of the Apocalypse' with their wars, food shortages, and
disease epidemics have been cutting down large numbers of the human
family since 1914.—Revelation 6:3-8.

Jesus also foretold the increase in crime that is experienced in all
lands. He said: "Because of the increasing of lawlessness the love of
the greater number will cool off."—Matthew 24:12.

Further, Bible prophecy foretold the moral collapse so evident
throughout the world today: "In the last days critical times hard to
deal with will be here. For men will be lovers of themselves, lovers of
money, self-assuming, haughty, blasphemers, disobedient to parents,
unthankful, disloyal, having no natural affection, not open to any
agreement, slanderers, without self-control, fierce, without love of
goodness, betrayers, headstrong, puffed up with pride, lovers of
pleasures rather than lovers of God, having a form of godly devotion
but proving false to its power . . . Wicked men and impostors will advance from bad to worse." (2 Timothy 3:1-13) All of that has come true right before our eyes.

Another Factor

There is another factor responsible for the huge increase in
suffering in this century. Coinciding with the beginning of the last
days in 1914, something happened to put mankind in even greater danger.
At that time, as a prophecy in the last book of the Bible relates: "War
broke out in heaven: Michael [Christ in heavenly power] and his angels
battled with the dragon [Satan], and the dragon and its angels [the
demons] battled but it did not prevail, neither was a place found for
them any longer in heaven. So down the great dragon was hurled, the
original serpent, the one called Devil and Satan, who is misleading the
entire inhabited earth; he was hurled down to the earth, and his angels
were hurled down with him."—Revelation 12:7-9.

What were the consequences for the human family? The prophecy
continues: "Woe for the earth and for the sea, because the Devil has
come down to you, having great anger, knowing he has a short period of
time." Yes, Satan knows that his system is nearing its end, so he is
doing everything he can to turn humans against God before he and his
world are put out of the way. (Revelation 12:12; 20:1-3)
How debased those spirit creatures are because they misused their free
will! How awful conditions have been on earth under their influence,
especially since 1914!

It is no wonder that Jesus foretold of our time: "On the earth anguish of nations, not knowing the way out . . . Men become faint out of fear and expectation of the things coming upon the inhabited earth."—Luke 21:25, 26.

End of Human and Demon Rule Near

How many Bible prophecies remain to be fulfilled before God destroys this present system? Very few! One of the last is at 1 Thessalonians 5:3, which states: "While they are talking of peace and security, all at once calamity is upon them." (The New English Bible) This shows that the end of this system will begin "while
they are talking." Unforeseen by the world, destruction will strike
when least expected, when the attention of humans is on their hoped-for
peace and security.

Time is running out for this world under Satan's influence. Soon it
will come to its end in a time of trouble of which Jesus said: "Then
there will be great tribulation such as has not occurred since the
world's beginning until now, no, nor will occur again."—Matthew 24:21.

The climax of the "great tribulation" will be God's war of
Armageddon. That is the time spoken of by the prophet Daniel when God
will "crush and put an end to all these kingdoms." This will mean the
end of all present human rulerships independent of God. His Kingdom
rule from heaven will then take over complete control of all human
affairs. Never again, Daniel foretold, will governing authority be left
"to any other people."—Daniel 2:44; Revelation 16:14-16.

At that time all satanic and demon influence will also cease. Those
rebellious spirit creatures will be put out of the way so that they
cannot "mislead the nations anymore." (Revelation 12:9; 20:1-3)
They have been sentenced to death and await destruction. What a relief
it will be for mankind to be free from their debasing influence!

Who Will Survive? Who Will Not?

When God's judgments are executed against this world, who will
survive? Who will not? The Bible shows that those who want God's rule
will be protected and will survive. Those who do not want God's rule
will not be protected but will be destroyed along with Satan's world.

Proverbs 2:21, 22
says: "The upright [those who submit to God's rule] are the ones that
will reside in the earth, and the blameless are the ones that will be
left over in it. As regards the wicked [those who do not submit to
God's rule], they will be cut off from the very earth; and as for the
treacherous, they will be torn away from it."

Psalm 37:10, 11 also says: "Just a little while longer, and the wicked one will be no more . . .
But the meek ones themselves will possess the earth, and they will
indeed find their exquisite delight in the abundance of peace." Verse 29 adds: "The righteous themselves will possess the earth, and they will reside forever upon it."

We should take to heart the counsel of Psalm 37:34,
which states: "Hope in Jehovah and keep his way, and he will exalt you
to take possession of the earth. When the wicked ones are cut off, you
will see it." Verses 37 and 38
say: "Watch the blameless one and keep the upright one in sight, for
the future of that man will be peaceful. But the transgressors
themselves will certainly be annihilated together; the future of wicked
people will indeed be cut off."

How comforting, yes, how inspiring it is to know that God really
does care and that soon he will put an end to all wickedness and
suffering! How thrilling it is to realize that the fulfillment of those
glorious prophecies is but a short time off!