*Allah's Mercy(God can forgive sins*

Islam is beautifully simplistic, it is the interaction between the individual and His Creator, there are no mediators in between. Therefore, when we sin, we believe that if we approach Allah directly in repentance, He will forgive us if we have left the sin and are sincere.

The Islamic perspective directly conflicts with Christian concept of original sin which looks to man as inherently sinful, carrying the“#sin”of Adam. From the Islamic viewpoint, every human being isresponsible for his/ her own actions and no soul will bear the burden of another.

Sins are those acts we deliberately incur by our choice of actions, we are responsible and hence personally accountable. In Islam there is no notion of redemption for one's sin by another. Each one is accountable for himself/herself .
 http://legacy.quran.com/99/7-8

By His grace and mercy, Allah has caused Islam to destroy the sins that came before it. When a disbeliever becomes Muslim, Allah forgives all that he did when he was a non-Muslim, and he becomes cleansed of sin.

http://legacy.quran.com/25/70
http://legacy.quran.com/8/38