As a Christian I gladly welcome questions like this. I appreciate non-believers desire to understand why Christian’s believe the way they believe. While they’re likely seeking a simple answer, the answer is rather complex. Why is water wet? From a scientific perspective, the answer is more complex than “it just is.” Christian’s believe God is the creator of the Heavens and the Earth. An immortal God created a mortal world and in its Genesis, he placed two mortal people that he gave the opportunity to make a choice to follow him or not. As mortal people they broke God’s trust through the Devil’s influence.
Though suffering isn’t good, God can use it to accomplish good. It is this same reason women experience pain (suffering) during childbirth (the Good). God sent His only son Jesus to live and experience the world. He worked, he suffered, he experienced tragedy. He was killed (suffered) for his beliefs, but returned (the Good) and will one day return to eradicate the world of all evil (the Greater). We don’t know why God does what he does, but we do know everything is a part of His bigger plan.
As a Christian, I’m not afraid to die, I’m afraid of dying. When I’m dying, I will suffer (John 16:33 ) in this mortal world, but I believe in my immortal God’s bigger plan and promise of eternal life for those who believe in him. (John 3:16) My sole purpose on Earth as a disciple is to advance Kingdome of God through good works. (Romans 8:28) I’m not perfect. The Devil will tempt me while God tests me. We are not all understanding, but He is. I don’t know God’s plan and why everything happens, but I believe in Him.
It’s not logical, it’s not scientific, but for me, that’s where reality ends and faith begins. My trust is in God.