The Kingdom of God is a future time that will last forever, where Jesus will rule over the whole Earth. The world will be made perfect, and all of today’s problems, including sorrow, pain and death, will disappear forever.
“And God will wipe away every tear from their eyes; there shall be no more death, nor sorrow, nor crying. There shall be no more pain, for the former things have passed away” -Revelation 21:4
See Also: Daniel 2:44, Isaiah 2, Isaiah 35, Psalm 72