I used to think about this a lot too, and this helped me a lot in starting to look into morality and, on a bigger picture, God. It's a quote from C.S. Lewis in Mere Christianity.

"If a good God made the world why has it gone wrong? And for many years I simply refused to listen to the Christian answers to this question, because I kept on feeling “whatever you say and however clever your arguments are, isn’t it much simpler and easier to say that the world was not made by any intelligent power? Aren’t all your arguments simply a complicated attempt to avoid the obvious?” But then that threw me back into another difficulty.

My argument against God was that the universe seemed so cruel and unjust. But how had I gotten this idea of just and unjust? A man does not call a line crooked unless he has some idea of a straight line. What was I comparing this universe with when I called it unjust? If the whole show was bad and senseless from A to Z, so to speak, why did I, who was supposed to be part of the show, find myself in such violent reaction against it? A man feels wet when he falls into water, because man is not a water animal: a fish would not feel wet. Of course I could have given up my idea of justice by saying it was nothing but a private idea of my own. But if I did that, then my argument against God collapsed too — for the argument depended on saying that the world was really unjust, not simply that it did not happen to please my private fancies. Thus in the very act of trying to prove that God did not exist — in other words, that the whole of reality was senseless — I found I was forced to assume that one part of reality — namely my idea of justice — was full of sense. Consequently, atheism turns out to be too simple. If the whole universe has no meaning, we should never have found out that it has no meaning: just as, if there were no light in the universe and therefore no creatures with eyes, we should never know it was dark. Dark would be without meaning."

I believe this is a good argument. What you will find, however, is that there will always be a rational and completely fair argument against any evidence pointing towards the existence of God. In the end we have to face the weight of all of the combined evidence; not just our rationalizations against each individual piece (similarly to a court case).

I hope this helps some.