In Islam, it is neither work alone nor faith alone get man to Paradise. It’s both actually, Allah says in the Quran:
But as for those who believe and do good works, for them are the Gardens of Retreat – a welcome (in reward) for what they used to do.(Sura 32:19)
See, belief is mentioned before good works, because actually good works alone do nothing if they were without belief, and belief without good works is not a serious belief. So actually good works are an indication of belief and that’s why in Islam we are accounted on our good and bad deeds, where bad deeds negate good deeds and the rank of every man in Paradise is dependent on his score of good and bad deeds, so actually good and bad deeds distinguish between believers in Paradise rather than meaning that man shall enter Paradise because of his deeds:
47. And We shall set up balances of justice on the Day of Resurrection, then none will be dealt with unjustly in anything. And if there be the weight of a mustard seed, We will bring it. And Sufficient are We as Reckoners.(Sura 21:47)
Associate this verse with this hadith:
Jabir reported that the Prophet of Islam said: “No good works of yours can ever secure heaven for you, nor can they save you from hell – not even me, without the grace of God.”

God promised us that if we believed and obeyed Him, we shall go to Paradise:
9. Allah has promised those who believe (in the Oneness of Allah – Islamic Monotheism) and do deeds of righteousness, that for them there is forgiveness and a great reward (i.e. Paradise). (Sura 5)
Now concerning sins, what if a man is a sinner? If he repented, God shall forgive him:
110. And whoever does evil or wrongs himself but afterwards seeks Allah’s Forgiveness, he will find Allah Oft-Forgiving, Most Merciful. (Sura 4)
If the sin was against God,then God has the right to forgive him, if the sin was against someone else as murder or insult for example, God won’t forgive it unless the one whom was sinned against forgives the sinner, otherwise, he shall take from his good deeds, if the sinner has no good deeds, he will receive the sins of the one whom he sinned against.

What if the sinner didn’t repent and doesn’t have good works that outweigh these sins?
116. Verily! Allah forgives not (the sin of) setting up partners in worship with Him, but He forgives whom he pleases sins other than that, and whoever sets up partners in worship with Allah, has indeed strayed far away. (Sura 4)
The only sin that shall let someone be eternally in Hell is Shirk which is associating partners with Allah and not believing Islam is the right religion. Other sins are either forgiven by God’s mercy or by going to Hell for some time till they are cleaned from the sins and enter Heaven afterwards.
So if they are Muslims even if they are sinners, they shall enter Paradise, but after being cleansed of their sins in Hell.
So simply salvation in Islam is first through faith, so that actually all Muslims shall go to Paradise, based on their deeds, they shall distinguish, some will be in the higher ranks of Heaven, some will be in lower ranks, some shall go to Hell first till he is cleansed out of his sins, then he shall go to Paradise. Deeds doesn’t mean that man can fulfill God’s blessings by his good deeds, but they are a sign of loyalty to God as long as they are associated with real faith, so that he gains God’s mercy that shall let him go to Paradise. But good deeds without faith shall not be accepted by God:
27. And (O Muhammad ) recite to them (the Jews) the story of the two sons of Adam [Habil (Abel) and Qabil (Cain)] in truth; when each offered a sacrifice (to Allah), it was accepted from the one but not from the other. The latter said to the former: “I will surely kill you. ” The former said: “Verily, Allah accepts only from the pious”
When I ask Christians, what is the need that God becomes a man and dies for our sins? The answer I always receive is: because God is just, He made an atonement for people to repent in the OT so forgiving people’s sins without an atonement is against His justice.
God has the right to forgive those who sinned against him as I have the right forgive anyone who insulted me, that has nothing with me being just or not, but actually people consider this as something good I do, so it has nothing to do with God’s justice, but it actually poses a couple of questions.
Christians cite this point of Jesus’ death with the atonements in the OT. According to Christian belief, who put the rule that there must be an atonement for blood so that the sins are forgiven, who put this rule? Isn’t He God? So how can this be a sacrifice? What Jesus did is not a sacrifice, but he just gave a solution to the problem God of Christianity caused? He is the one who put the rule and it was found to be impractical, he did what he did to solve the problem. So either God of Christianity didn’t know the consequences of this rule, so he found a problem and solved it, which is against God’s omniscience, or that he actually knew and did what he did to make a show that he loves you.
The second thing, what I know is that people are accounted for their intention, if you do something and this deed gives consequences other than who you intended it to be, then you are actually accounted for your intention not for the consequences, for example if I robbed a guy walking in the street and gave what I stole as a present to a friend of mine, then I discovered that the guy I robbed actually stole this stuff from my friend, am I a thief or a noble guy who wanted to help my friend? For sure a thief, as my intention was just to rob a guy and I didn’t know the other part of the story. That’s exactly what the death of Jesus was about, it wasn’t intended by the Jews to make a sacrifice or atonement so that Jesus takes away their sins, they were just looking to him as someone who shall destroy their leadership and positions and they wanted to get rid of him. So the whole action can be accounted as an atonement, but as murder crime, and this has nothing with what Jesus himself intended, because he is not the one who implemented the action, otherwise he would kill himself.
http://jesus-is-muslim.net/concept-o...-christianity/