The ethical conduct of Zeus and the ethical teachings of Jesus were completely opposite. Jesus’s teachings of God were based in ethics, and the actions of Zeus had little to do with any ethical system.
Zeus, according to classical Greek and Roman writers, operated on virtually no ethical guidelines or principles. He did as he pleased, constrained by neither god nor man. He was sovereign over all other gods, and over all of mankind. He frequently raped women and gods alike, such as the rape of Io as described in Ovid’s Metamorphoses.
Zeus administered negative sanctions unpredictably, and it was often difficult or even impossible to know what actions would be rewarded or punished by him. In ancient times, it was believed that the deciding factor in wars and other conflicts was which gods were on your side. The victory of one faction was attributed to the victory of the gods on one side over the gods of the other. However, the way the gods chose their sides was based entirely on whims and matters of seemingly small importance, and not on the fulfillment of ethical criteria by the side in question.
Many of the negative sanctions and punishments imposed on mankind by Zeus or any of the other Gods were based mostly on revenge. In Ovid, the story of the deluge, which superficially paralleled the story of Noah and the flood, was based on Zeus’s revenge on mankind for its evil. In the story of Noah, God wiped out all evil in the world in order start anew and repair mankind. There was no one selected to be spared from Zeus’s destruction, contrary to the story of Noah, and it was mostly by accident that a couple survived, and were able to restart the human race.
Zeus is obviously capable of evil, as is shown in much of Greece’s classical literature. He does not follow any guidelines, and is not bound to justice. His punishments are often based on whims or on revenge, not on the violation of certain laws.
Jesus taught that God is perfect, and incapable of evil. Evil is the only thing that God cannot do. Jesus also taught that God is ethically predictable, and always a force of good, and will always be against the forces of evil, with no exceptions. Unlike Zeus, God’s sanctions are based on a very specific set of laws which are known to mankind. If someone violates one of these laws and does not make reparation, that person will be punished. Likewise, if someone obeys the laws, and makes reparation if he does breach a law, then he will be rewarded. The punishments given by God are always completely just. These positive and negative sanctions are completely consistent, and do not rely on God’s “mood”. His actions are based on a system of ethics, not whims.
In addition to being completely just, Jesus taught that God is also completely merciful. This seems to be a contradiction, for how can something be fully just and fully merciful at the same time? The answer is, according to Christian doctrine, that it is a mystery, and we will never be able to comprehend it. All we can do is believe.
Jesus’s ethical teachings of God differed greatly from the way Greek and Roman writers portrayed Zeus. Zeus is portrayed as a monster, who was at many times evil. His treatment of mankind is unpredictable, administering positive and negative sanctions on whims. Mercy did not factor into Zeus’s system, and his justice was not based on ethics. Jesus’s teachings showed a very different system, one based on a God who was good, and both merciful and just. His justice was based on ethics and the violation or adherence to certain laws which are known to mankind. In conclusion, The God of Jesus’s teachings and the god portrayed by Greek and Roman writers were irreconcilably opposed.