The scribes and Pharisees were admired for their zeal, concern for purity, perfection and devotion to oral tradition. But this made them arrogant because they looked down upon those who were ignorant of the Law, thus they avoided the company of sinners. Since they are men of the Law they think they deserve the love of God. It is, for them, their privilege.
We, too, are Pharisees when we present ourselves as just, good, religious yet blind to the situation of our reality that we are sinners. Of what use will our prayers be if we do not have compassion? We do not kill physically but our hearts are full of anger, hatred and judgments against others. We open our mouth to sing hymns yet that same mouth we use to gossip and destroy others. If we want to be upright externally, we have to be more zealous and perfect than the Pharisees. This is a herculean task. Legal observance is not enough. We may fall into arrogance because everything depends on our strength. Christ came for those who cannot help themselves. He died for sinners. If we are not sinners then the effort of Christ is of no value for us. Like the Pharisees we conduct ourselves as hypocrites.