Christianity and Islam

Jesus: Jesus is just a prophet and not the Son of God. He is only a prophet to the Jews who was not crucified but was caught up into Heaven. God placed a substitute in his place on the cross. Many Muslims feel the substitute was Judas. Jesus is the Messiah who is coming at the end. He will kill all the Jews, Christians and pigs break all crosses get married and die 40 years later and be buried in Medina next to Mohammed.
The Resurrection will follow.
157 That they said (in boast), "We killed Christ Jesus the son of Mary, the Messenger of Allah"- but they killed him not, nor crucified him, but so it was made to appear to them, and those who differ therein are full of doubts, with no (certain) knowledge, but only conjecture to follow, for of a surety they killed him not-
158 Nay, Allah raised him up unto Himself; and Allah is Exalted in Power, Wise- Surah 4:157-158,
So peace is on me The day I was born, the day that I die, and the day that
I shall be raised up to life (again)!
Sura 19:33

Holy Spirit:  The angel Gabriel is recognized as the Holy Spirit within Islam, or as some commentators think angels in general.
If ye two turn is repentance to Him, your hearts are indeed so inclined; but if ye back up each other against him, truly Allah is his Protector, and Gabriel, and (every) righteous one among those who believe, and furthermore, the angels will back (him) up.
Sura 66:4
Salvation: The Muslims believe in salvation by obedience to Allah. Mohammed will intercede on the behalf of Muslims before Allah. In a scale, Allah will weight the sins and good deeds to determine the punishment. Time in Hell will be necessary to pay for sins that outweigh good deeds. After which the “Muslims” will be accepted into Paradise. Non-Believers will go to Hell with no hope of escape. Those who die in Jihad or Holy War will go directly to Paradise where 72 virgins will be awaiting him.
Al-Miqdam ibn madikarib Ma'dikarib (Hadith)
MISHKAT AL-MASABIH (Hadith)
Allah's Messenger (peace be upon him) said, "The martyr receives six good things from Allah: he is forgiven at the first shedding of his blood; he is shown his abode in Paradise; he is preserved from the punishment in the grave; he is kept safe from the greatest terror; he has placed on his head the crown of honour, a ruby of which is better than the world and what it contains; he is married to seventy-two wives of the maidens with large dark eyes; and is made intercessor for seventy of his relatives."
Tirmidhi and Ibn Majah transmitted it.
MISHKAT AL-MASABIH (Hadith)
Allah's Messenger (peace be upon him) said, "The lowliest of the inhabitants of Paradise will be he who has eighty thousand servants, seventy-two wives, and for whom a round pavilion of pearls, chrysoprase and rubies as large as the distance between al-Jabiyah and San'a will be set up." By the same isnad he said, "Those who are to go to Paradise, who die whether young or old,
Sin: Man is born sinless and all people are Muslims at birth. But lack of obedience to Allah is sin. Sin is by action only and not by nature.
Sources of the Quran:
Where did the Quran come from? The Quran claims Allah is its  source of the Quran is a copy of  an identical book is written in Heaven that was given Gabriel to give to Mohammad in intervals.
105 We sent down the (Quran) in truth, and in truth has it descended: and we sent thee but to give glad tidings and to warn (sinners).
106 (It is) a Quran which we have divided (into parts from time to him), in order that thou mightest recite it to men at intervals: we have revealed it by stages.
Surah 117:105-6
History gives us a different answer. The Quran’s content can be traced to sources in existence prior to Mohammed birth.  A few of these sources can be found below.

Jewish sources of the Quran
1. Visit by the queen of Sheba to Solomon  as recorded in Sura 27:17-30

And before Solomon were marshalled his hosts, of Jinns and men and birds, and they were all kept in order and ranks.
18 At length, when they came to a (lowly) valley of ants, one of the ants said: O ye ants, get into your habitations, lest Solomon and his hosts crush you (under foot) without knowing it.
Sura 27:17-18
This same story is recorded almost verbatim in the Talmud work II Targum of Ester 1,2
2. Abraham saved from Nimrod’s Fire as recorded in the following Suras 2:260, 6:74-84, 21:52-72, 19:42-50, 26:69-79, 24:15-16, 37:81-95,

We bestowed aforetime on Abraham his rectitude of conduct, and well were we Acquainted with him.
52 Behold! he said to his father and his people, what are these images, to which ye are (so assiduously) devoted? 53 They said, we found Our fathers worshipping them.
Sura 21: 52-53
The source for this story is from the Midrash Rabbah on Genesis
3. Cain and Abel Sura 5:30-35
Then Allah sent a raven, who scratched the ground, to show him how to hid the shame of his brother. Woe is me said he; was I not even able to be as this raven, and to hide the shame of my brother? then he became full of regrets
-Sura 5:30
The source of this story can be found in the book
Pirke Rabbi Eleaszer in the Midrash. The only difference being that the crow shows Adam not Cain how to bury Abel.
4. Harut and Marut The two angles of Babylon.
They followed what the evil ones gave out (falsely) against the power of Solomon: the blasphemers were, not Solomon, but the evil ones, teaching men magic, and such things as came down at Babylon
the angels Harut and Marut.
Sura 2:109
This same story is taken from the Midrash Yalkut the only difference being the two angels named are Shamhazi and Azael. But the names of Harut and Marut were two idols worshipped far back in Armenia. They were assistants to the female goddess Aspandaramit. The Zoroastrians regarded her as the spirit of the earth.
Heretical Christian Sources
5. The Seven Sleepers, or Companions of the Cave. Surah 18:9-26
9 Or dost thou reflect that the companions of the cave and of the inscription were wonders among our Signs?
10 Behold, the youths betook themselves to the cave: they said, our Lord bestow on us mercy from thyself, and dispose of our affair for us in the right way
11 Then we draw (a veil) over their ears, for a number of years,
in the cave, (so that they heard not): Sura 18:9-11
The legend is Greek and is found in the Latin work of Gregory of Tours. Seven men of the city of Ephesus take refuge from persecution in a cave during the reign of Decius (249-251 AD) they wake in the reign of Theodorus II 447 AD. Christianity being the faith of the empire. This was a mere story to illustrate the rise of Christianity in the Roman Empire.

Zoroastrian Sources
6. Quranic view of Paradise Sura 55:72, 56:22

Round about them will (serve) youths of perpetual (freshness),
18 With goblets, (shining) beakers, and cups (filled) out of Clear flowing fountains:
19 No after ache will they receive therefrom, nor will they suffer intoxication:
20 And with fruits, any that they may select;
21 And the flesh of fowls, any that they may desire.
22 And (there will be) Companions with beautiful, big, and lustrous eyes
Sura 56:18-22
The picture of Paradise with beautiful virgins waiting for men is not found in any of the Old or New Testament but can be traced to the Zoroastrian concept of Paradise Paries or Fairies –spirits in bright array and beautiful, to captivate the heart of a man. The name houry is derived from an Avesta or Pahlavi source. As well as jinn for genii and bihvisht (Paradise) signifying in Avestic “The better land”.