Our world is comprised of myriad people, each one constituting a dynamic and complex world unto themselves.
The nature of such a system is that for each person fulfilling a mitzva, there is someone committing a sin.
We are unable to see the big picture: where the world stands, and where we each stand vis-a-vis the world.
Despite this (or perhaps even on account of this), we must constantly be aware of the nature of things:
each holy act pulls the entire world upward, and vice versa.
Even a single action – and we will never know which one has the capacity to change everything in a split second, for good or otherwise.
Rabbi Adin Steinsaltz