The key biblical passage is Romans 8:19-22, which says:
For the creation waits with eager longing for the revealing of the sons of God. For the creation was subjected to futility, not willingly, but because of him who subjected it, in hope that the creation itself will be set free from its bondage to corruption and obtain the freedom of the glory of the children of God. For we know that the whole creation has been groaning together in the pains of childbirth until now.
To understand what Paul is talking about here, you have to go to the very beginning of the Bible. Genesis 1:1 says 'In the beginning, God created the heavens and the earth.' After the description of God creating all things, at the end of the chapter we're told that God looked at all He made and declared that it was very good. There were no flaws or defects whatsoever; no suffering, no pain, no tears, no evil, no death.
But then Adam and Eve did something horrifyingly evil -- preferring a piece of fruit over fellowship with their Creator God -- that God not only sentenced them to death, but also cursed the entire created world because of their sin: "cursed is the ground because of you; in pain you shall eat of it all the days of your life."
Whereas once there was no suffering or evil, now every human dies. every human suffers innumerable pains and hardships before death, rivers overflow and sweep villages away, hurricanes destroy whole cities, tsunamis kill hundreds of thousands of people in one night, AIDS, cancer and heart disease kill millions of people old and young, droughts and famines bring millions to the point of starvation, and helpless babies are born without breath in their lungs or blood in their veins.
If we could see all the pain and misery of this world, we would collapse under the weight of it. This endless groaning is a perpetual reminder of the horror of human sin against our loving, benevolent God. When we see the misery of this fallen world, we should mourn over our sin, which is the cause of all this futility and pain.
But even in God's original curse on the created world, there is a window of hope. In Eden, God said to the soul-destroying, creation-corrupting serpent: "I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel."
God promised that one day He would send a Redeemer to crush the serpent and undo all the futility that has resulted from that horrible sin in Eden. Paul knew this, so he said in Romans 8:20, "For the creation was subjected to futility...in hope that the creation itself will be set free from its bondage to corruption and obtain the freedom of the glory of the children of God." The day is coming when the whole creation will be set free from its corruption and decay (all the disease and droughts and tornadoes and death that infests this material world).
Paul knew that the promised Redeemer was Jesus Christ, who came to destroy all the works of the devil (1 John 3:8), not just in individual human lives but in the entire cosmos. Christian writer Neal Plantinga describes this cosmic healing like this:
"[It will be a] new age in which human crookedness would be straightened out, rough places made plain. The foolish would be made wise, and the wise, humble. They dreamed of a time when the deserts would flower, the mountains would run with wine, weeping would cease, and people could go to sleep without weapons on their laps.
People would work in peace and work to fruitful effect. Lambs could lie down with lions. All nature would be fruitful, benign, and filled with wonder upon wonder; all humans would be knit together in brotherhood and sisterhood, and all nature and all humans would look to God, walk with God, lean toward God and delight in God. ”
Everything will be the way it ought to be, the way God originally designed it to be. It will be a New Heavens and a New Earth, where the glory of God will be our all in all, and where everything sad in this decaying world will come untrue and be transformed into greater glory. That is the hope of redemption, and this great hope was purchased on the Cross when Jesus Christ shed His blood as a substitute for hopeless sinners.
Jesus is not only reconciling individuals to God, but He is also determined to put right everything that has gone wrong in this sin-soaked, misery-filled world. And because of His bodily resurrection, we know that no power of hell nor any scheme of man will be able to stop Him from this cosmic restoration. He will one day, in the words of Revelation 21:5, make all things new. This hope is for all who unite themselves to the crucified and risen Jesus through faith.
What a magnificent hope it is...but while we wait in hope for that wonderful day, we groan. And the groaning is both a reminder of the horror of human sin, and the hope of redemption that is found in Jesus Christ alone.
That is why we must remember to groan, today and every day until Jesus comes again to make all things new.