Why is there human suffering?

This is one of the most common spiritual questions people ask (along with what happens after we die?). The answer is both simple and yet profound.

The Bible says that all suffering is the result of sin. All suffering, all grief and misery is ultimately traced to the sin of mankind and the schemes of Satan. More specifically, suffering results from human sinfulness, demonic agency and God's curse upon the earth (as a result of sin), which conspire together to yield all negative and harmful consequences in Creation. 

The consequences of sin are only corrected by the power of Christ. The Bible says those who believe in Christ will be saved from this life in a future day, and in our new glorified bodies we will see the end of our suffering. Later, in the New Heavens and Earth, the Lord will eliminate all pain and suffering brought about by sin and the devil in all Creation:

Rev. 21:3 And I heard a loud voice from the throne, saying, “Behold, the tabernacle of God is among men, and He will dwell among them, and they shall be His people, and God Himself will be among them, 
Rev. 21:4 and He will wipe away every tear from their eyes; and there will no longer be any death; there will no longer be any mourning, or crying, or pain; the first things have passed away.” 
 

When the Lord returns and sets up the Kingdom, we will be glorified and our suffering will be over. Once the New Heavens and Earth arrive, all suffering will be ended because all sin and rebellion will be done away with. 

Until that day arrives, suffering will continue. The Lord is not pleased to see suffering, but He endures it with us waiting for His plan of salvation to play out through all generations. As Peter says in response to those who might criticize Christ's delay in returning to end suffering:

2Pet. 3:9 The Lord is not slow about His promise, as some count slowness, but is patient toward you, not wishing for any to perish but for all to come to repentance. 
 

Regarding Satan, he cannot repent for the Lord has not granted him repentance. Only when the Lord grants repentance can it happen, as Paul teaches:

Acts 5:31 “He is the one whom God exalted to His right hand as a Prince and a Savior, to grant repentance to Israel, and forgiveness of sins. 
 

Acts 11:18 When they heard this, they quieted down and glorified God, saying, “Well then, God has granted to the Gentiles also the repentance that leads to life.” 
 

2Cor. 7:9 I now rejoice, not that you were made sorrowful, but that you were made sorrowful to the point of repentance; for you were made sorrowful according to the will of God, so that you might not suffer loss in anything through us. 
2Cor. 7:10 For the sorrow that is according to the will of God produces a repentance without regret, leading to salvation, but the sorrow of the world produces death. 
 

2Tim. 2:25 with gentleness correcting those who are in opposition, if perhaps God may grant them repentance leading to the knowledge of the truth, 

The repentance that leads to salvation and a changed heart is a work done by God Himself in the heart, and unless God grants repentance, a person (or angel) cannot repent. Furthermore, the Bible says it is not in God’s plan to grant mercy to fallen angels like Satan:

Heb. 2:16 For assuredly He does not give help to angels, but He gives help to the descendant of Abraham. 
 

Scripture quotations taken from the (NASB®) New American Standard Bible®, Copyright © 1995, 2020 by The Lockman Foundation. Used by permission. All rights reserved. www.lockman.org