which is older zoroastrianism or hinduism?

and in what way did they and the Greek philosophers impacted Christianity and Islam?

Hinduism

Zoroastrianism has the battle of good vs. evil as one of its most important themes. This impacted Christianity by introducing the idea of a good god vs. an evil devil.

Hinduism is considered the oldest religion in the whole world.

Does it matter ?

These are two questions, I will answer the first.

Hinduism predates Zoroastrianism by thousands of years. The difference is apex 2000-5000 yrs.

Okay, I'll answer a little of the second question.

Christians believe that Jesus (pub) was both man and god. This is incorrect, he was a man only. Anywho, they believe this way because it's what I call "Greek residue."

You see, the Gentiles in Biblical times believed in Greek philosophies, one of them being dualism. Dualism = belief that man and god can exist as one. Example: Pharaoh. The early Christians converts were Gentiles, and were attracted to Christianity not because of Hebrew philosophy, but because of Greek philosophy. At the time, the intellectual world believed in Greek philosophies. It was what the "upper crust" believed, what the intelligent people believed, and one of these philosophies was dualism.

For the church to attract new believers, they blended their pagan ideas with Christian/Hebrew ideas. Otherwise, they wouldn't have attracted nearly as many. Sooo, blending god + man was one way Gentiles became Christians.

Hinduism is older as an organized and codified religion, but they both share common mythological roots. There was a pro to Indo-Iranian religion which links them.

http://en.wikipedia.org/wiki/Proto-Indo-Iranian_religion