They’re His children.

“What man of you, having a hundred sheep, if he loses one of them, does not leave the ninety-nine in the wilderness, and go after the one which is lost until he finds it? And when he has found it, he lays it on his shoulders, rejoicing. And when he comes home, he calls together his friends and neighbors, saying to them, ‘Rejoice with me, for I have found my sheep which was lost!’ I say to you that likewise there will be more joy in heaven over one sinner who repents than over ninety-nine just persons who need no repentance.”

- Luke 15:4-7 NKJV