I tell them that God did not do this. He made a perfect world. Satan lives in rebellion against God. He could not stand the creation of a perfect world with man in a harmonious relationship with God. So Satan tempted Eve to do the one thing God told her not to do. And she did it. So did her husband Adam. As a consequence of their action, they had to leave the perfect Garden of Eden and live in a now fallen world.
Even then, God loved man so much that He enacted a plan to restore that perfect world. The plan culminated in the coming of God’s own Son to redeem man. Those who believe in him get to live with God forever. Those who do not believe in Him, don’t. So here is my answer: it is not God’s fault. He gave us the free will to make choices. Adam and Eve made bad ones. So do we. God promised He would fix it, and He did.
But some of those questioning do not believe this story. They do not believe in God. So I tell them to quit blaming Him. If He does not exist, then He is not the cause of this messed-up world. If He does exist, the fallen world is not His fault or His choice. And He will make it right.
So the choice is always yours to make. Believe God is real and that He will fix the world we have destroyed, or believe He does not exist and just live with the way things are. No hope, no future, no life.