I believe that the notions of a forgiving God and a vengeful God are related to realities of the human condition. Grace reflects the potential for dramatic, almost instantaneous turns for the better in our lives. Even the most wicked person can change and be a better person for it. Being a better person, means living a better life.
A murderer sitting in his jail cell can accept responsibility for his crimes, feel deep, legitimate remorse, and at that moment begin living the life of a good person. That such peace is available to even the murderer is a manifestation of Grace.
Similarly, there are consequence for our actions. No matter our good intentions. Even if we made a mistake. Consider a parent that walks away from a baby in a tub, and the baby drowns. His behavior, his actions, may have been no different than the actions of many others who did not experience this tragedy. Still, he caused the death and will be tormented and inconsolable as a result of his actions. That is a manifestation of a God's Wrath.
I do not believe that God caused the baby to drown. I do not believe that God loves the murderer more after he has changed his life. I think these are thoughts that were more appropriate in pre-scientific times when nature seemed to be a conscious actor.
I think we can recognize that God doesn't thrust tragedy upon and still retain an understanding that there are consequences for our actions. There is an application of this thinking to our political actions I will try to address later.