Even a small amount of poison can spoil the entire cake.
Yes... but nobody is infallible either... so if you take that analogy to it's nth degree, your isolated, alone and easy prey because you've got a drop of poison within yourself too, that's why we have recourse to the sacrament of confession throughout our lives, so we should be careful with how harshly we treat others IMO, especially when we know there was no malice involved.
God Bless