opinion has an effect
Humility is the great sin of the modern age. Whether it’s “I’m okay; you’re okay” or “I’m the king of the world,” humility is on the other end of that spectrum. Many in the secular world find the notions of Christianity — Catholicism in particular — about the true, fallen nature of humanity to be distasteful because it offends the relatively modern sense of the inherent goodness in humanity. I think it probably has more to do with the humiliation of humility than it does with supposed dignity and inherent moral goodness. This is, of course, not to say that all individuals in today’s culture lack humility — just the prominent ones, the ones we as a society generally look up to.
Humility has as its object to eliminate that which is imaginary in spiritual progress. There is no harm in thinking ourselves far less advanced than we are: the effect of the light is in no way decreased thereby, for its source is not in opinion. There is great harm in thinking ourselves more advanced, because then opinion has an effect.
Having too positive an opinion of ourselves distracts us from the goal almost all religions set before us: the purification of our will. It not only distracts us; it deceives us.