Why did God allow Adam  and Eve to sin?

This is a deep mystery. All that we know is that God, when He created  mankind, He did not make them like robots that automatically obey  all commands. He gave them the ability to choose freely whether to  obey God or not. That is why He gave them the choice of abstaining  from eating the fruit of the tree of knowledge of good and evil (and  so obeying God), or eating the fruit (and so disobeying God). Now  the vital question is: God knew beforehand that man would disobey  Him. Why did He allow it? We must of course understand that it was  not the will of God that man should sin. If we say that, it will mean  that we make God responsible for sin and that can never be true.  But the question why He did not intervene is a very deep mystery that  we cannot explain. God alone knows what He is doing and why. His thoughts  are not our thoughts. But we must remember that God, who is a just  God who punishes sin, also revealed Himself after the fall as a God  with amazing grace, because He immediately looked for the sinners  and promised that the seed of the woman (Christ) would crush the head  of the snake (Satan) Genesis 3:15. This happened when Jesus died  on the cross and arose as the triumphant Christ, the Conqueror of  Satan and sin (Luke 23:33 24:35). Whosoever believes the Gospel,  is saved forever from the power of Satan and sin. You also have the  ability to make good and bad choices, and to live with the result  of those choices. Where you made the wrong choice, Christ has opened  the way to full forgiveness for you. Come to Him with your heavy load  of care, and He will give you rest (Matthew 11:28).