“Some people think they can imagine a creature which was free but had no possibility of going wrong; I cannot. If a thing is free to be good it is also free to be bad. And free will is what has made evil possible. Why, then, did God give them (mankind) free will? Because free will, though it makes evil possible, is also the only thing that makes possible any love or goodness or joy worth having. A world of automata – of creatures that worked like machines – would hardly be worth creating. The happiness which God designs for His higher creatures is the happiness of being freely, voluntarily united to Him and to each other … .
And for that they must be free.”
[ taken from Mere Christianity by CS Lewis; Copyright 1952; Harper Collins Publishers; page 49 ]