'Children' in the Bible

My children, of whom I am again in birth-pains till Christ is formed in you,

Now this Hagar is the mountain Sinai in Arabia, and is the image of the Jerusalem which now is: which is a servant with her children.

For it is in the Writings, You who have never given birth, be glad; give cries of joy, you who have had no birth-pains; for the children of her who has been given up by her husband are more than those of the woman who has a husband.

Now we, brothers, as Isaac was, are the children of the undertaking of God.

So, brothers, we are not children of the servant-woman, but of the free woman.