Matthew 5:4
Blessed are they that mourn: for they shall be comforted.
Strong's Ex. Conc. No. 3996
MOURN: properly, grieve over a death; (figuratively) to grieve over a personal hope (relationship) that dies, i.e. comes to divine closure ("ends"). ("Mourn over a death") refers to "manifested grief" so severe it takes possession of a person and cannot be hid.
In John 16:16-33 Jesus is speaking to His disciples regarding His imminent death, resurrection, ascension, and return. Which, of course, they understood none of.
Many would rejoice over Christ's murder. For murder it was. He was too controversial to be allowed to live, so the local religious higher-ups conspired to kill Him. Matthew 26:2-3.
Then His disciples, His followers, would be mourning their loss while they who had conspired to kill Jesus would be rejoicing in His death, believing their problems to be over.
Upon Christ's resurrection, the disciples would rejoice; the murderers and they that condoned the mock trial and crucifixion would fear. When Christ left Earth to return to His Father, the disciples again rejoiced.
The Jewish religious leaders spread lies about Jesus while the disciples spread the Truth. As it was then so it is today.
For nearly 2000 years the faithful followers of Christ have preached the return of the King of Kings. The closer the time for His return the louder the earth groans and the world endeavors to destroy those who speak the Truth of the Gospel of Salvation through Jesus Christ.
We read in Revelation that when the two witnesses are killed, the people partied for three days. But then. Revelation 11:1-14.
When all is said and done as The Word has revealed it to us, they who came against God and His Son and His people will be no more. The world will no longer exist and a new earth will take its place. Revelation 21.
Until that time happens we who believe that Jesus Christ is Lord and Savior will continue to proclaim the Good, Good News. Come to Jesus. Come and be filled with The Bread of Life. Come and quench your thirst with the Living Water. Come and be empowered with The Holy Spirit, for The Spirit calls to you, too. Come and be loved by God.
Revelation 22:17
The Spirit and the bride say, “Come!” Let the one who hears say, “Come!” And let the one who is thirsty come, and the one who desires the water of life drink freely.