Children get cancer, "innocent " people are murdered, there are all types of examples of moral evils we can clearly see. Where is God, you ask. Why does He not do something? He is doing something, right in us. He is revealing evil, the absence of Grace. He is revealing to us that we know “this should not be”. This is not “right”. But, there is the problem. For there to be an objective “right” or “wrong, evil”, there must be an objective, absolute, moral order and therefore there must be a God, Creator of all space and time. If there is no God, there can be no cause of the absolute, objective, moral order; everything would be meaningless and relative.
This God must be the infinite perfection of every good virtue we can see and know. Therefore He must be the infinite perfection of the good virtue demonstrated by a good father who wants to share with his children and others, the good things he has found . Therefore God wants to share with us, HIMSELF, infinite Goodness. He created us with free will because He is Good and He wants us to choose to be good by His grace and He shows us what happens when we choose evil. We bring misfortune on us and others. We can focus on the misfortunes we see, the evils, or we can focus on the end where God will be all in all, everything to everyone (CCC 130, 1 Cor. 15:28). When “partial knowledge ceases” (CCC 314), we will know how God brought about the best history possible without violating anyone’s free will.
We can focus on the evils we see, or we can focus on what we would have already received from God’s Justice if it were not for God’s mercy, hell fore ever and ever and ever… because of one sin. Because of one sin, we cannot deserve heaven, yet, because of the mercy of God we still have a chance for heaven.
We can focus on the evil of a child’s cancer or the “undeserved sufferings” of someone else, or we can focus on the possibility that that person is in heaven, counting their sufferings in this world as nothing, because by God;'s mercy and goodness, they are in heaven forever, and ever and ever.
What should we focus on? That we know there are objective “right actions” and “evil actions” and we should choose the right ones and throw ourselves on His Mercy and ask for mercy for everyone else? Or we can be small minded and say, " because I do not see how God can bring good in the next life from all of this suffering in this life, and I am only concerned with this life, I will therefore rebel further against God".