10 “See that you do not despise one of these little ones. For I tell you that their angels in heaven always see the face of my Father in heaven. [11] [a]
12 “What do you think? If a man owns a hundred sheep, and one of them wanders away, will he not leave the ninety-nine on the hills and go to look for the one that wandered off? 13 And if he finds it, truly I tell you, he is happier about that one sheep than about the ninety-nine that did not wander off. 14 In the same way your Father in heaven is not willing that any of these little ones should perish.
Dealing With Sin in the Church
15 “If your brother or sister[b] sins,[c] go and point out their fault, just between the two of you. If they listen to you, you have won them over. 16 But if they will not listen, take one or two others along, so that ‘every matter may be established by the testimony of two or three witnesses.’[d] 17 If they still refuse to listen, tell it to the church; and if they refuse to listen even to the church, treat them as you would a pagan or a tax collector.
18 “Truly I tell you, whatever you bind on earth will be[e] bound in heaven, and whatever you loose on earth will be[f] loosed in heaven.
19 “Again, truly I tell you that if two of you on earth agree about anything they ask for, it will be done for them by my Father in heaven. 20 For where two or three gather in my name, there am I with them.”
The joy of God
Saint John Chrysostom, Homilies at Matthew Homily LIX (Bucharest, 1994), pp. 690-691
Thus if God rejoices so much of the salvation of one of these little ones, why to despise those who are so dear to God when you should even give your life for them instead? You tell me that he is a helpless man and an ordinary one ? But that is why you should do everything to save him; because Christ too left the 99 sheep; the salvation of so many sheep had no power to cover the loss of a single one. Saint Luke, the evangelist says that he took it and put it on his shoulders and said: « I tell you that in the same way there will be more rejoicing in heaven over one sinner who repents than over ninety-nine righteous persons who do not need to repent. ».
He showed His great care for the lost one by the fact that he left the saved ones and for this reason he rejoices even more of his salvation.
Source: http://ziarullumina.ro.