A: How do you know when the devil is your father?Q: When God is not your Father...
Ye are of your father the devil,
John 8:44
Q: And what will you do if the devil is your father?
A: and the lusts of your father ye will do.
John 8:44
Q: So what is the Inverse Relationship that applies here?
A: You will do God's will if He is your Father.