What makes Christianity so special and different?

Alright so it seems that there is some evidence of God. But how do we know that Christianity is the religion that has the right idea about Him? I was once told that Christianity as a whole is mainly stolen from bits of Zoroastrianism and Judaism and that it's only original and wise contribution was the golden rule.(I personally found this a bit unlikely but I didn't know enough about theology and history to argue.) What makes Christianity so special and different?

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This is a huge topic on which much can be said. To over-simplify tremendously, I'd offer three points:

1. The life, death resurrection of Jesus
2. The extraordinary growth of the Church, from a persecuted minority to taking over the Roman Empire to the massive worldwide following she has today, not least in countries like S Korea and China.
3. Philosophically: if God exists He is obviously not incompetent. So one of the major purported communications from God to humanity is likely to be genuine, probably the one with the largest number of adherents spread over all the world, who are not kept in line by threats of violence.

Defintion of "God"

Before one can debate the existence of the divine ie. god, one must understand the definition of "god". I understand the word "god" to be an abstract like "love" ,"justice" ,etc, therefore, the definition eludes universal clarity and acceptance. With so many people having many definitions of "god", how can anyone come to a universal agreement as to what god is, much less debate whether or not he exists? How is "God" in your understanding defined? and how can it be considered valid, with so much disagreement over what is meant by the word "God"

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NB Response: I think the simplest philosophical “definition” of God is The Ultimate Creator.
Christians, and I think almost all theists, believe that anything that exists or has existed and is logically capable of having been caused was created directly or indirectly by God. (as the Bible puts it “through him all things were made, and without him was not anything made that was made”)

It is perfectly obvious that either there is no Ultimate Creator or there is exactly one, and that the question “who created God” is meaningless. Equally God is not an “abstract noun” but the creative ground of our entire being, and that God can hardly be less than a person, though may of course be more than a person. He is certainly not an “abstract noun”!