I think we all understand that Christians believe in sin, Wiccans do not. You have asked how a Wiccan can stray from such a path. I'll try to keep it succinct. If one thoughtfully examines the Rede, it quickly becomes apparent that almost every action has the potential to harm some creature in some way. Drawing breath can kill micro-organisms that float unseen, in the atmosphere.
Drinking water does the same thing.
One could choose to marry, and ultimately bring pain and suffering on future generations of children by way of an unhappy union. There is literally no way that one could possibly foresee all circumstances and avoid harming anyone. Yet, that is what the Rede demands. In my opinion, the answer is obvious. The Wiccan must choose.