Unfortunately piety has a bad name, primarily because there are a lot of people in the world who try to conform their lives to the manifest will of God in a way that simply kills charity in their souls. We've come to call them pharisees and we are fools if we presume the proper pronoun is "them" rather than "us."
Fr. Benedict Groescel, in Stumbling Blocks or Stepping Stones describes two traps the pious (among whom I number myself) can get into. The first is less serious in itself and, with a reasonable amount of self awareness and intentionallity, it can be overcome. After discussion how great personal suffering can lead one to become more compassionate toward the sinner and the sufferer of the world, he says:
There is a strange and often misunderstood problem here for organized religion and especially for the Church. Much of the world's sorrow comes from sin and misbehavior. A devout person who tries to lead an orderly life and fulfill his or her responsibilities is likely to experience less sorrow than the disorganized, irresponsible person. Religious practice and morality remove a person from a sizeable portion of the world's sorrow. 'Happy are they who walk according to the law of the Lord,' and unhappy are they who do not. Unfortunately, this can lead the devout to be less sorrowful and, consequently, less compassionate than the poor sinners of the world.
This is almost an accidental, automatic fault. It can be overcome, as Fr. Groeschel points out, by reading good literature and opening your eyes to the plight of the poor and intentionally entering into solidarity with the poor by divesting one's self of some of the incidental benefits of a devout life.
The saints, combatting their own possible complacency, purposely avoided the comfort of their virtuous lives by sharing in the misery begotten of sin. In any society the difference between the pious and the saintly is often the degree of compassion and acceptance of another's pain through sorrow that has strangely linked the saintly and the sinful.
This is not an argument against piety and devotion, but it is a statement about the true nature of piety and devotion--that it is centered on trust in God and compassion towards all, especially the sinner.
The second, and more insidious trap for the pious, as Fr. Groeschel points out at the beginning of his book, is the belief that pious and devout behavior somehow automatically excludes the Christian from the number of those in the world who are fully capable of great evil.
Believers can be deceived by their own virtue. Although Christ our Lord warned that not everyone who called him 'Lord' would enter the kingdom, good Christians have persisted in believing that they were somehow 'above it all.'
This can lead to, among other things, an attempt to separate one's self from the sinner to avoid contamination, as if you don't thereby bring the contamination with you, because it is in you all along. We try to create hermetically sealed, utopian Christian communities and try to avoid contact as much as possible with those poor, sinful wretches out in the world who might contaminate us.
I once belonged to a charismatic group that exhibited this tendency. The presumption seemed to be that because they had been baptized in the Spirit, they had been cleaned of the effects of original sin. I can still remember being at a prayer meeting. One of the leaders went over to the window in the building we were in, looked out over the city and stuck out his tongue at the flesh, the world and the devil, implying that none of these realities had any sway among the hundreds in that room. Unfortunately, the same group was soon to be rocked by a sexual abuse scandal that brought one of the leaders down.
The answer to this temptation, according to Fr. Groeschel is humility and compassion. We must enter into the subjective reality of the sinner, know his suffering and his limitations, his sadness and despair. The word John Paul II used was solidarity. Disdain for the sinner, even the egregious and unrepentent one, is not compatable with Christian virtue. And we need to realize that we are not so much different than they are. We might be guilty of sin that we, in our pride, are not even aware of.
I thoroughly recommend the book and anything by Groeschel.