I'm not tackling the argument against athiesm here but I've worked on the problem of evil before and I've reached an understanding that works for me.
So working on the assumption that there is a (loving) God/s and also that we know for a fact that there is a certain amount of evil in the world, what reasons would God/s have for creating it and allowing it a place in the world?
Well firstly, we are limited by our own concept of evil. It stands to reason that there will always be a worst in human behaviour. Evil is what we perceive as the worst we can imagine. But supposing the top layer of what we see as evil was removed? The next layer would rise to the top of our perception. Even if evil as we know it was taken away, we would still percieve evil. So on this basis, it is entirely possible that true evil has not been allowed into the world and we just cannot know that because we can't comprehend that which does not exist. It is therefore at least possible that a loving God/s have chosen to spare us true evil.
Then we have to consider the nature of our relationships with the deities. Is love about giving everything freely or is it a greater love to provide us with the ability to develop into the true potential of who we are as a creation. Is hardship a necessary part of the learning progress of each of us as a spiritual entity? Are our Gods wise enough to know that without the adversity of evil we would be stunted as a creation? Surely the hallmark of loving Gods is to allow us the tools to become the very best that we can.
It is argued that more people would believe in the Gods without the problem of evil to contend with. But I would question whether that belief has any value if it is a belief borne out of an inability to question. It is easy to accept the Gods if life goes entirely your own way, it is harder when you meet hardship and pain on your path. But to come through adversity with your belief intact and indeed strengthened, that is a belief worth offering to your Gods.
If we were programmed to love God/s. If it was a belief we were given rather than something we come to of our own volition, we would be little better than automata. Certainly not a creation of significant worth. We would be like robots, unable to question our own beliefs. We would have little value to the Gods in this situation. They gave us the choice to interpret our world through the eyes of a believer or not, as we choose. By asking for a perfect creation we are asking to be in a position where we don't have to question. We are asking to be robots. There is little value in such a life.
In my opinion the thing that makes us pretty special as a creation is our ability to think for ourselves and to choose our own directions in life. Free will is possibly the greatest gift we could be given. It is a logical impossibility to have free will and also to be prevented from using that free will in the direction we choose. Many if not most of the evils in the world are created by ourselves. To mitigate that would be to remove our freedom to have free will. That would be wrong. Free will has a greater value than living in world free of evil. Imagine your thoughts, your choices, your entire identity stripped from you. Again you are reduced to nothing better that a robot. No loving God/s could ever make the choice to take that from you. And if the consequence of that free will is that sometimes people do bad things to good people, that still is, in my opinion a better world than the alternative.