This is a comparison of the differences between Christianity and ancient Greek religion.
Modern Greece is predominately Christian today but ancient Greece had a very different belief about religion. The first major difference between these two belief systems is the presence of polytheism in Greek religion. The ancient Greeks believe in many, many gods. They had gods for just about everything you could imagine. The gods of Olympus are extremely famous and there are plenty of things based on them. the Pantheon of gods are the most famous but they also had many lesser known gods and even demigods such as Hercules.
Christianity, on the other hand, is a monotheistic religion, meaning we worship one God. We believe that He is the creator of all things and He is the One keeping watch over everything that happens on earth. In ancient Greece, if you were having trouble as a fisherman then you would call on Poseidon or if you needed help with love then you called on Aphrodite. As a Christian, you pray to only one God for all things you need help with.
The second major difference between Christianity and traditional Greek religion is the conduct of the gods. According to the Greek myths and documents concerning their gods, the deities are constantly committing adultery, flying into passionate rage, or doing other irrational human-like things. Christians believe that God is perfect and does all things out of justice and love. He does not do anything ridiculous like falling in love with a human and killing her husband because He is not capable of sinning.
How the gods are worshiped is another deviation of these religious practices. In ancient Greece, many things were done outside of what is typically considered worship for Christians. Namely, the erection of graven images. The Bible specifically states that there are to be no graven images of God constructed. This rule has been broken of course as all rules are but for the most part, it is stuck to in Christianity. The Greeks fashioned tons of statues and structures depicting their gods.
The final difference I am going to mention has to do with the way God approaches his people. In Greek religion, the gods must be called upon if their help is desired. They come down to earth of their own accord on occasion but it is usually on errands of mischief rather than peace. And if humans do something against their will they must be appeased by sacrifices.
Christianity teaches that God sent His only Son to live on earth and give us a chance to follow Him and turn from our wickedness. Instead, we were blinded by our sin and they cried for him to be crucified. He suffered although He was sinless and died. On the third day after he had died he rose from the grave and went back to Heaven. But he carried the weight of our curse on his shoulders and our sins were forgiven. Doubtless, you have heard that story countless times if you are a Christian but it is a beautiful thing, and Christianity is the only religion where a god comes down to earth to save us instead of humans bending over backward to appease them.