A common reason many people give for doubting the existence of a creator is the prevalence of suffering in the world.there have been outright evil, great suffering, cruelty and bloodshed throughout the centuries and these had made many question the existence of God and why He really permit this suffering.
From the beginning, the book of Genesis record that , "God created the world without suffering" he gave man and woman duties to carry out in the garden that was a paradise of itself, this He did with lay down rules "Genesis be 1:28" They were created with perfect body and mind which was free from sickness, death , old age , evil thoughts etc. Thus the human race will be United family, all living in perfect health on Earth.
They were not designed with the ability to govern themselves, they needed to accept the direction of their maker. And as long as they stayed within the guidelines set for them by their creator, life was assured to be peaceful, in Harmony, successful and it continuity was assured.
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Until the fall of man which separated God from men. They pulled off from the "source of life, happiness, peace joy etc" and choose to live an independent life and God allowed man to learn the meaning of the choice they made. Without their Creator substaining power, a gradual breakdown of mind and body began. In time they grew old and died -Genesis 3:19. Man separation from God made them fall from perfection.
As they began to give Birth, the children reflected what the parents have become ,"imperfect" so the first human became like a defective pattern. This imperfection , along human separation from God and his laws opened the floodgates of human folly. This has resulted to mankind history filled with sorrow, sickness, death etc Roman 5:12
Is this to say that wickedness originated entirely with human? No, there are other factors to it. Before the creation of human, God has created angels . Some of these angels rebel and where thrown down. Infact it was one of the Angels (Satan) that went as far as luring Eve into eating the tree. And for the past 6000 years, this same attitude of Satan has influenced mankind advancing a policy of ruin.-Revelation 12:9
Some believers may go as far as to ask why so long? Why has God permitted suffering about 6000 years now? The answer might be that , He wants human to experience the unstability of men rules or that no charges would be made by human that they were not given enough time to develop a workable government and necessary technology to bring peace. And this has been fruitless over centuries now and comes down to prove that human rule independent of man's creator is unsatifactory .
God has promised a blessed future ahead , free from sickness, war , death and cruelty for those who are His own. so the suffering, war etc are only for a mean time until God once again rule the Earth and renew us into a new being with perfect body and mind once again.