The only group of people Jesus was really harsh with were the Pharisees. The reason was that they should have known better. As experts in religion they should have realized that external observance of a lot of man-made laws is not the way to please God. In their practices they were self-righteous and complacent.
St Paul makes the same point in our first reading today. His lesson is summed up by saying, Do you presume on God's kindness and forebearance? Do you not know that God's kindness is an invitation for you to repent?
God has surely been kind to us. He has given us the great gift of faith. God surely shows us forebearance. No matter what our sins may be, He is always eager to forgive us. If we have an image of God as an all loving and forgiving Father, we are quite correct.
And yet we must not be self-righteous, nor must we become complacent. To put it another way, we must not presume to take advantage of God because He is so kind and merciful. Rather the desire to grow even more holy and more dedicated to God is to move in the right direction. The desire to respond more fully to such a loving God is what is pleasing to Him.
Lord, grant me humility to accept You in others and free me from an attitude of self-righteousness.