Well usually, if something comes first, and several other things come AFTER that something, with so many undeniable similarities to that first something, then those several other things can rightly be accused of copying that original first something.
There's no way to prove that claim conclusively. But if you take the comparison between Zoroastrianism and the Abrahamic religions, their similarities are so close to identical that it's hard not to make that claim. It's not like I can take a novel, rename the characters, and call it a new book, can I? That's exactly what the Abrahamic religions supposedly did. For Christianity, their Rapture is so similar to the apocalypse in Zoroastrianism; their idea of Jesus is almost identical to Ahura Mazda and Spenta Mainyu; their idea of Satan is almost identical to Angra Mainyu; the prosperity that is to come from the resolution of the Rapture is completely identical to that of resolving the apocalyptic battle in Zoroastrianism.
Stick in a virgin giving birth, a calcification, rising from the dead, and claims of a Trinity, and somehow, you've got an entirely new religion.
The belief in Satan comes from the Zoroastrian religion religion that has a big influence on Christianity and Muslim belief
1 UNKNOWN possibly Enoch according to some soybeans
2 KRISHNA appeared in India between 2,000 and 3,000
BC
3 MOSES advents in Egypt about 1330 B,C
4 ZOROASTER, came in Iran (Persia) between 1,000
500 B,C
5BUDDHA, was born in India about 500 B C
6 CHRIST the birth of Christ was between 4 B.C and 1 A.D
7 MUHAMMAD, was born in Arabia about 570 A.D
8 THE BAB,born in Shiraz, Persia, October 20,1819 A,D
9 BAHA'ULLAH, born in Tehran, November 12, 1817
1 UNKNOWN possibly Enoch according to some soybeans
2 KRISHNA appeared in India between 2,000 and 3,000
5BUDDHA, was born in India about 500 B C
There are six Abrahmic religions see if you can work out which three are not
I think only Christian is a western religion, derived from Greek and Roman religion.Elements of Zoroastrianism were incorporated in the Greek and Roman religion prior to birth of Christianity.