Christianity and the Scarlet Letter

In English we have started reading The Scarlet Letter; when we were doing the pre reading stuff in class my English teacher brought up the elements of the Christian movement of Martin Luther and specifically a guy named John Calvin. John Calvin was the founder of Calvinism and the specific belief of pre-destination, my teacher who knows that I am a United Methodist and petty familiar with John Wesley; she told me that Wesley took this idea. I am kind of puzzled because I thought that Wesley taught that Christians were saved by Grace, but then how does pre-destination come into play? One point my teacher brought up was that pre-destination does not really mean what we think it is, that pre-destination is simply that God knows in advance who will accept Grace. Potentially all people could be saved by Grace, so how does God already know who will accept it? This is some deep theology that I'm contemplating, and possibly more to come; I'll let you know how the rest of the book goes.