The way we live shows who our father is.
When we exhibit a lifestyle in public and in private that is consciously lived for God in recognition of the Lord Jesus as an eternal being in oneness with the Father in heaven, it cannot be hid that we are the children of God.
On the contrary a child of the devil displays the character of the evil one towards the Son of God, the Immanuel; still tempting Jesus by casting doubt and questioning his claims and the testimony of the one who bears witness to his sonship, none other than his Father; and rejecting the testimony of the Jehovistic “I Ams” which are no less the claim to Deity.