Christianity is the following of Christ's example. It stems from Judaism. Satan comes from ealy biblical times, beginning with genisis.
The sun worshipers (Zoroastrians) had nothing to do with it at the time, as they didn't exist.(they stem from Persians in the Iran region) Perhaps you should read better material, rather than stuff on web sites which likes to confuse the faiths and run them into each other. Your ignoring about 5,000 years of history.
And when was Genesis written? And do you have proof that it was not edited later to include this concept? Hint: it was later edited to reconcile the early polytheistic beliefs with the more modern monotheistic beliefs.