The Pharisees and Sadducees came up, and testing JESUS
They asked HIM to show them a sign from heaven.
But HE replied to them
When it is evening, you say, ‘it will be fair weather, for the sky is red’
And in the morning, ‘there will be a storm today, for the sky is red and threatening’
Do you know how to discern the appearance of the sky
But cannot discern the signs of the times?
An evil and adulterous generation seeks after a sign
And a sign will not be given it, except the sign of Jonah
And HE left them and went away.
Matthew 16:1-4

In this passage of Scripture we saw religious leaders wanting JESUS to prove that HE was indeed the Messiah sent by GOD, by providing a miracle from heaven (such as when fire came down from heaven to the earth, proving Elijah was the prophet sent by The true GOD in Israel (1 Kings 18:36-39).

Our Beloved LORD JESUS WHO had already performed many miracles up to this point, had provided sufficient proofs that HE was WHO HE claimed to be. Yet these religious leaders still did not believe in HIM. Knowing that sufficient proof of the truth would never be enough for hardened and unbelieving hearts, HE simply stated “An evil and adulterous generation seeks after a sign; and a sign will not be given it, except the sign of Jonah.” HIS statement to the unbelieving religious leaders was expounded upon in Matthew 12:39-41:

But HE answered and said to them,
An evil and adulterous generation craves for a sign
And yet no sign will be given to it but the sign of Jonah the prophet
For just as JONAH WAS THREE DAYS AND THREE NIGHTS IN THE BELLY OF THE SEA MONSTER
So will The SON of Man be three days and three nights in the heart of the earth
“The men of Nineveh will stand up with this generation at the judgment, and will condemn it
because they repented at the preaching of Jonah
and behold, something greater than Jonah is here

The Pharisees and Sadducees did not believe in our Beloved LORD JESUS CHRIST, doubting that HE spoke absolute truth. To this very day, unbelievers doubt the BIBLE as being both absolute (100% true with no exceptions-Psa 119:160, Jhn 17:17) and infallible (always perfect, always accurate, no errors – Psa 19:7). And because of their unbelief, unbelievers will:
Test or question the truth, not because they want to learn, but for the purpose of discrediting it (Luk 11:16, Mat 12:38–42, Luk 16:27-31). Those who reject the truth will always be deceived (1 Kin 18:36-39, Rev 13:11-14 Mal 4:5, Mat 17:10:13, 2 Ths 2:10-12).
Mock the truth, choosing to ridicule rather than earnestly search for it (Php 3:17–19, 2 Tim 4:3-4, 2 Pet 3:3-7, Jud 1:18). Insulting the truth rather than clinging to it, will always lead to destruction (2 Chr 36:15-17, Pro 1:20-33, 2 Ths 1:8-9).
Ignore or reject the truth, as they are not willing to turn from their evil ways. They reject both HIM (Heb 12:25-28) and HIS messengers (Zec 7:11-14). Which leads to both physical (Luk 17:26-27, Gen 7:17-23, 2 Pet 2:5) and spiritual death (Rev 21:8).

Only through The BIBLE (The WORD of GOD), can we discern (understand or recognize) the times we are currently living in, and understand what we should do (1 Chr 12:32). Discernment of the times we are currently living in, brings:

1. Knowledge of what we should do (1 Ths 5:1-8), and what type of people ought we to be (2 Pet 3:14-15).
2. Insight through both The SPIRIT of GOD and The WORD of GOD, enables us to see and clearly understand people, circumstances, and events all around us (Psa 119:99-100, Isa 41:20, Dan 11:33, Dan 12:10, 1 Cor 2:14-16).
3. Watchfulness that keeps us from being caught off-guard; unprepared; asleep (Mat 24:42-44, Mrk 13:32-37, Luk 12:35-40, Rom 13:11).
4. Peace which surpasses all understanding (Php 4:7), the peace which GOD gives (Jhn 14:27). We are not filled with fear like those who have no discernment (Luk 21:25-26), instead we should be filled with expectation (Isa 26:3, 2 Ths 3:16).

Just one final point, fully understanding that we are in the very last days does not mean we should give up and quit living. We should do quite the opposite, following the lead of our Beloved SAVIOR JESUS CHRIST. Knowing that HIS departure from this life was near, HE did not quit, HE continued to minister until HIS very last breath (Jhn 13:1-20, Jhn 19:28-30).

But what about the non-ministry part of our lives, how should we live, knowing that time is short? We will answer this in two parts. First, we should live wisely (Psa 90:12). You might be wondering what it means “to live wisely or have a heart of wisdom.” It means to understand our lives are fleeting (Job 14:1-2, Psa 144:4, Jam 4:14), therefore being careful how we live (Pro 19:16, Eph 5:15-17), because we know we will appear before the judgment seat of CHRIST, and give an account of how we lived (2 Cor 5:10). Second, every part of your life should be ministry. To minister means to serve, to provide, take care of, to distribute, to do the things necessary to sustain life. Whether it is physical life, emotional life or spiritual life, we are each called to minister throughout our lives.

But when these things begin to take place
Straighten up and lift up your heads
Because your redemption is drawing near
Then HE told them a parable
Behold the fig tree and all the trees
As soon as they put forth leaves
You see it and know for yourselves that summer is now near
So you also, when you see these things happening
Recognize that the Kingdom of GOD is near
Truly I say to you, this generation will not pass away
Until all things take place
Heaven and earth will pass away
But MY WORDS will not pass away
Luke 21:28-33