Romans 8:9-11, 14

You, however, are not in the flesh, but in the Spirit, since the Spirit of God lives in you. But if anyone does not have the Spirit of Christ, he does not belong to Him. Now if Christ is in you, the body is dead because of sin, but the Spirit is life because of righteousness. And if the Spirit of Him who raised Jesus from the dead lives in you, then He who raised Christ from the dead will also bring your mortal bodies to life through His Spirit who lives in you.

All those led by God’s Spirit are God’s sons.