Why?

The very first effort of Satan to overthrow God’s law — undertaken among the sinless inhabitants of heaven — seemed for a time to be crowned with success. A vast number of the angels were seduced; but Satan’s apparent triumph resulted in defeat and loss, separation from God, and banishment from heaven. PP 331.1

When the conflict was renewed upon the earth, Satan again won a seeming advantage. By transgression, man became his captive, and man’s kingdom also was betrayed into the hands of the archrebel. Now the way seemed open for Satan to establish an independent kingdom, and to defy the authority of God and His Son. But the plan of salvation made it possible for man again to be brought into harmony with God, and to render obedience to His law, and for both man and the earth to be finally redeemed from the power of the wicked one. PP 331.2

Again Satan was defeated, and again he resorted to deception, in the hope of converting his defeat into a victory. To stir up rebellion in the fallen race, he now represented God as unjust in having permitted man to transgress His law. “Why,” said the artful tempter, “when God knew what would be the result, did He permit man to be placed on trial, to sin, and bring in misery and death?” And the children of Adam, forgetful of the long-suffering mercy that had granted man another trial, regardless of the amazing, the awful sacrifice which his rebellion had cost the King of heaven, gave ear to the tempter, and murmured against the only Being who could save them from the destructive power of Satan. PP 331.3

There are thousands today echoing the same rebellious complaint against God. They do not see that to deprive man of the freedom of choice would be to rob him of his prerogative as an intelligent being, and make him a mere automaton. It is not God’s purpose to coerce the will. Man was created a free moral agent. Like the inhabitants of all other worlds, he must be subjected to the test of obedience; but he is never brought into such a position that yielding to evil becomes a matter of necessity. No temptation or trial is permitted to come to him which he is unable to resist. God made such ample provision that man need never have been defeated in the conflict with Satan. PP 331.4

There hath no temptation taken you but such as is common to man:
but God is faithful, who will not suffer you to be tempted above that ye are able;
but will with the temptation also make a way to escape,
that ye may be able to bear it.
KJV 1 Corinthians 10:13