I get some questions from time to time - specially from non-believers - who ask why God could not have foreseen that Adam would fall or whether is was an experiment that went horribly wrong.
Of course it is neither of these and I wish to discuss this in a logical and simple way, although I must say from the start that there are also other aspects of this that we do not know, for God also had other considerations which He did not tell us of or which we may not understand.To get to grips with this, we should first look at the fall of Israel as a nation which will give us some insight into the fall of Adam.
The facts of Israel as a woman, is that God married her and that he wanted to gather he under His wings as a hen gathers her chickens - now that is real close. (see Luke 13:34)Israel however had other plans and a free will and drifted into idol worshop with their golden calf (Ex. 32:4), and whoredom as in Num 14:33 And your children shall wander in the wilderness forty years, and bear your whoredoms, until your carcases be wasted in the wilderness.
There are also many other instances of this.
Eventually, God had to give her a bill of divorce : Jer 3:8 And I saw, when for all the causes whereby backsliding Israel committed adultery I had put her away, and given her a bill of divorce; yet her treacherous sister Judah feared not, but went and played the harlot also. v:9 And it came to pass through the lightness of her whoredom, that she defiled the land, and committed adultery with stones and with stocks.
This error was due to their free will and was expected as anyone with a free will will sin as we have seen with the angels who rebelled against God even before Adam was created. A third of them rebelled against God and went into damnation.If you take anyone into a house of sin with enough time and money, liquor and women or whatever other distraction we may conjure up, chances are about 100% that he/she will sin. So sinning with free will is a given and God knew it even better than we do.
However, God wanted mankind to have free will so that He can have a friend likened unto Himself who could, with Him, enjoy creation and enjoy God. It was so important to God to give mankind free will, even although He knew man would sin. The only thing he needed to do then was to send His Son for their sins, which He knew He would do. If one reads about the fall of Adam one sees that God immediately had a plan to save man and one gets the impression that God all along had that plan, even before Adam sinned. Gen 3:15 And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel. (This is a reference to the crucifixion of Christ)
Returning to Israel. God had to leave Israel for a moment to save the gentiles and then return to them again as Paul so aptly describes.
Rom 11:11 I say then, Have they stumbled that they should fall? God forbid: but rather through their fall salvation is come unto the Gentiles, for to provoke them to jealousy. v:12 Now if the fall of them be the riches of the world, and the diminishing of them the riches of the Gentiles; how much more their fulness? v:25 For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. (In part means - God also had other considerations)Now we are ready to return to Adam and the able words of John Wesley will tell the story more fully.
'Was it not easy for the Almighty to prevent it ? - He certainly did foresee the whole ... But it was known to Him, at the same time, that it was best, upon the whole, not to prevent it. He knew that ... the evil resulting from the former was not as the good resulting from the latter, - not worthy to be compared to it. He saw that to permit the fall of the first man was far best for mankind in general; that abundantly more good than evil would accrue to the posterity of Adam by his fall; that if 'sin abounded' thereby over all the earth, yet grace 'would much more abound'; yea, and that to every individual of the human race, unless it was his own choice ..... Mankind in general have gained, by the fall of Adam, a capacity for attaining more holiness and happiness on earth than it would have been possible for them to attain if Adam had not fallen.
Unless all the partakers of human nature had received that deadly wound in Adam, it would not have been needful for the Son of God to take our nature upon Him ... there would have been no room for that amazing display of the Son of God's love to mankind .. It could not then have been said, to the astonishment of the hosts of heaven 'God so love the world that He gave His Son.'
... What is the necessary consequence of this? It is this : There could then have been no such thing as faith in God thus loving the world, giving His only son for us men, and for our salvation ... the whole privilege of justification by faith could have had no existence'
My own words : As we know from the duality of life on earth, that after Adam ate from the tree of knowledge of good and evil, that good and evil would co-exist on earth, and it is for us to prevail over evil.
Just so free will and sin will co-exist, but we must choose.