Life is a process of karma
Life is a process of karma as well as a means to work out the result of the past karma. The karma theory, as believed by the Hindus, can be understood in its rudiments through your statement, 'As u sow, so u reap'. However, in practice, it could be complex process, wherein the karmas of several persons are intertwined and entangled which defies a simple definition. All the human beings have to work out their karmas and until that is completed, he will be born again and again. More accretion of fresh karmas will further delay his salvation. Repentance and other forms of ethical living will indeed aid in cleansing of your karma or sin. Repentance is the first step towards washing of your karma.