A man, then, who remains the same and yet prattles to himself
about the change for the better that he has undergone in baptism
should attend to what Paul says,
“If anyone thinks himself to be something, when he is nothing, he deceives himself” (Gal 6:3).
For you are not what you have not yet become.
The Gospel says of the regenerate, however, that
He gave all those who received Him the power to become God’s children (Jn 1:12).
Now the child born of someone certainly shares his parent’s nature.
If then you have received God and have become His child,
let your way of life testify to the God within you.
Make it clear who your father is!
The marks by which we recognize God are the very ones by which a son must show his relation to Him.
He opens His hand and fills every living thing with joy (144:16).
He passes over ungodliness  (Mic 7:18).
He repents of evil (Joel 2:13).
The Lord is good to all, and His mercies are upon all His works” (Ps 144:9).
“The Lord my God is upright, and there is no wrongdoing in Him” (Ps 91:16).
This is what fathers do for children.
Similar sayings are scattered through Scripture for our instruction.
If you are like this, you have genuinely become a child of God.
But if you persist in displaying the marks of evil, it is useless to babble to yourself about the birth from above.
St. Gregory of Nyssa