'Child' in the Bible

Now I say, That the heir, as long as he is a child, differeth nothing from a servant, though he be lord of all;

So you are no longer a slave but a child, and if you are a child, then you are also an heir because of what God did.

But the child of the slave woman was born according to the flesh and had an ordinary birth, while the son of the free woman was born in fulfillment of the promise.

For it is written, "Rejoice, thou barren woman that bearest not, break forth into a joyful cry, thou that dost not travail with child. For the desolate woman has many children--more indeed than she who has the husband."

But just as then the child born according to the flesh persecuted the one born according to the Spirit, so also now.