Okay, so the claim would be that Islam and all other "monotheistic" religions copied Zoroastrianism. First to start off we have to consider the fact that God sent a messenger/one who warns to every people to teach the religion of God and to also warn them of consequences if they are ignorant and deny etc... This is so that they can't say "we wern't warned," like many try to say after a test. (We can see this in normal exams were if they're not taught something they would think they would be unjustly treated.)
And therin they will cry aloud: "O our Lord! Take us out, we will do good, (righteous deeds), not (the wrong) we use to do before," "Did We not grant you a life long enough for whoever would reflect and be mindful to reflect and be mindful? In addition, a warner came to you(to warn against this punishment). Taste then (the consequences of your heedlessness); for the wrongdoers have none to help them (against it)." 35:37
You going to have a lot more groundwork to establish some of the statements you make. Examining Mohammed's life and thinks he said, as according to the Haddiths does not produce a compelling case for him being a messenger from God. The Quran itself does not provide a compelling case either...
DrSoccerball said:
"God sent down only one religion but allowed it to be changed by humans because it was only meant for those people and that specific time period. (While leaving the religion in its complete form when humanity was ready for its message AKA Islam. This is the Islam (we believe) that all the Holy prophets followed.(Dan would disagree).)"
So it is very possible that this religion was sent down by God so it may show some similarities like Islam shows with Christianity. But since we don't know for certain we can't claim it to be the case. Also according what Dan said it can also be disputed.
<1> You said: "God sent down only one religion but allowed it to be changed by humans because it was only meant for those people and that specific time period." Of course I do disagree, as would every other Christian. How is what you are saying any different from what the Ba'hai people believe for instance? The same logic could be applied to Islam, it is a very slippery slope. Just be careful... Mind you, Mormons also believe what you just said to be true, except their "prophet" is Joseph Smith not Mohammed.
<2> There is a massive discontinuity between Judaism/Christianity and Islam. While Judaism and Christianity are clearly related, there is no engagement within Islam, with any of the major tenants of these older "revelations", with of course the exception of Jesus' death which the Quran denies; and secondly, there only be one
unitarian God.
Continuing on that... it seems very unusual that the Quran would quote sometimes non-inspired and sometimes non-canonical, a mix of apocryphal and pseudigraphic texts such as the Midrash, Talmud or the Arabic Infancy Gospels (non-canonical second century texts, that are non-canonical), which is reasonable for me*, but maybe not for you, but never actually quotes the Old Testament or New Testament directly, even though it . It is odd, very peculiar, that the author of the Quran (whoever that may be), would be familiar with the non-canonical and sometimes heretical texts, but not actually with the canonical and orthodox texts, particularly the Law and the Prophets.
(*yes the Bible quotes the book of Enoch, Jasher and other non-canonical texts, but makes no mention or does not act as if these books are inspired)
And I don't think you answered his question very well, but okay.