Romans 8:13-17

For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live.

For as many as are led by the Spirit of God, they are the sons of God.

For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.

The Spirit itself beareth witness with our spirit, that we are the children of God:

And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.