I'm not going to argue whether or not God exists, because it is a matter of faith, and if one's mind is set on not believing, one will not believe.
But I want to answer to the best of my ability about why God allows suffering.
We were created with free will. We aren't forced by God to do anything. We can worship Him, or can choose not to; it is up to us. Of course, according to the Bible, Adam and Eve chose to disobey God. The temporal punishment for that original sin is cause for some of our suffering. We are in a broken state.
Then, there is Satan, who can tempt us to disobey God, just as Adam and Eve were tempted. Even causing such bad things to happen can cause us to ask that question of why they happen, which is what Satan wants.
So, it is our choice. We can choose to follow God, but that's not a free ticket to get out of all suffering. But God will use that suffering to help us draw closer to Him, and thus have more peace and happiness.
God created the world, knowing it may rebell, and it did. God tries to draw those back to Him who will listen, and follow His law to the best of their ability.
So, God is very "nice." It is not His fault the world is so evil. In fact, He does everything He can to draw it back to Him. He came into the world, became just like any one of us in everything except sin, suffered in all the ways we do, and even worse, and died for our disobedience and sin. I think that's pretty nice.
Again, if you don't believe in God, this reasoning will seem ridiculous, but I'm not here to argue if God exists.