Hindu to Christian

I am editing a friend's Masters Thesis for him. He is from Nepal but has come to the states for a couple of years to work on his ThM. The title is "An Analysis of the Idea of the Atonement in Hinduism in the Light of Christianity." It is actually quite fascinating. I came across this one section in his paper that I thought was especially probing...

"Does it really make much of a difference when a Nepali Hindu becomes a Christian? Both believe in doing good works, even in loving one’s neighbors; it’s just a question of motive. Hindus accumulate merit from their good deeds to counterbalance their bad deeds. Christians says that a life full of good deeds cannot outweigh even a single sin. We must first seek forgiveness from God relying on his mercy shown to us through his son, Jesus Christ. Then, once forgiven, he enables us to do good out of thankfulness and love for him who died for us."

To someone looking in from the outside - what's the difference? Why is the change necessary?