So far the only fundalmental difference I see between Islam and Christianity it the belief that Jesus is or isn't God in the flesh.
While this is a huge difference in terms of how each religion views salvation it is the only real difference that I can find.
I hope every knows who believes what but just in case:
Christians believe that Christ is God in the flesh, who was ressurected and went to heaven and that Salvation is through him only.
Jesus
Luke 1:26-38
The Birth of Jesus Foretold
29Mary was greatly troubled at his words and wondered what kind of greeting this might be. 30But the angel said to her, "Do not be afraid, Mary, you have found favor with God. 31You will be with child and give birth to a son, and you are to give him the name Jesus. 32He will be great and will be called the Son of the Most High. The Lord God will give him the throne of his father David, 33and he will reign over the house of Jacob forever; his kingdom will never end."
34"How will this be," Mary asked the angel, "since I am a virgin?"
35The angel answered, "The Holy Spirit will come upon you, and the power of the Most High will overshadow you. So the holy one to be born will be called[
a] the Son of God. 36Even Elizabeth your relative is going to have a child in her old age, and she who was said to be barren is in her sixth month. 37For nothing is impossible with God." 38"I am the Lord's servant," Mary answered. "May it be to me as you have said." Then the angel left her.
Salvation
John 14:6
6Jesus answered, "I am the way and the truth and the life. No one comes to the Father except through me
Islamist believe that Jesus was a prophet. They do believe that he was born to the virgin Mary and that salvation is through deeds and by Allah
Jesus
Maryam 19: 16-21
19:16 AND CALL to mind, through this divine writ,Asad(19,12) Mary. Lo! She withdrew from her family to an eastern place
19:17 and kept herself in seclusion from them,Asad(19,13) whereupon We sent unto her Our angel of revelation, who appeared to her in the shape of a well-made human being.Asad(19,14)
19:18 She exclaimed: "Verily, 'I seek refuge from thee with the Most Gracious! [Approach me not] if thou art conscious of Him!"
19:19 [The angel] answered: "I' am but a messenger of thy Sustainer, [who says,] `I shall bestow upon thee the gift of a son endowed with purity.'"
19:20 Said she: "How can I have a son when no man has ever touched me? - for, never have I been a loose woman!"
19:21 [The angel] answered: "Thus it is; [but] thy Sustainer says, `This is easy for Me;Asad(19,15) and [thou shalt have a son,] so that We might make him a symbol unto mankind and an act of grace from US.Asad(19,16) And it was a thing decreed [by God]:
Salvation:
Surah 5:9
5:9To those who believe and do deeds of righteousness hath Allah promised forgiveness and a great reward
Shura 42:26
42:26 and responds unto all who attain to faith and do righteous deeds; and [it is He who, in the life to come,] will give them, out of His bounty, far more [than they will have deserved], whereas for the deniers of the truth there is [but] suffering severe in store.
Anfal 8:29
8:29 O you who have attained to faith! If you remain conscious of God. He will endow you with a standard by which to discern the true from the false,Asad(8,29) and will efface your bad deeds, and will forgive you your sins: for God is limitless in His great bounty.