God gave man choice in the life of this World, but most of people chose to be wrong-doers and transgressors and trespassers on the rights of others, so they kindled wars till now, which is against God's commandments.
Moreover, God created this material World for the purpose of the next ethereal spiritual and lasting life in the Hereafter.
And it is a test for man: to see will he be thankful for His bounties or will he be blasphemous and deny His blessings.
In addition, God guides the man who is worthy of guidance ( the kind to the poor and needy).. so as to believe in God as One God without associate or peer.
And God misguides the wrongdoer and the transgressor, so that this one will become atheist or idolater.
So while the World is temporary and is a test of man: will he persevere patiently and be thankful ... or blaspheme and denies the blessings of his God?
Therefore, in the life in the World, man will be tested by distress and hardship once, and by prosperity and good health at another time.
While in the Hereafter, man will not become ill or suffer in Paradise for the guided to the 'exclusive devotion to God alone.'
But the second category of people: the wrongdoers and disbelievers will suffer in the Next Life.
Quran 21: 35, which means:
(
We try you [once] with evil and [another time with] good, so as to check you c, then to Us you shall be returned [following your death d.])
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c To see will you be patient in distress, and be grateful in the prosperity, or will you blaspheme and be ungrateful?
d And We will then reward you according to your work: the grateful for his gratitude, and the ungrateful for his non gratitude and blasphemy.