to Timothy, my true child in faith: Grace, mercy, and peace, from God our Father and Christ Jesus our Lord.
The two relationships with God that Paul cited, as our Father and our Lord, are especially significant in this letter. Timothy had a tendency to be fearful, so the reminder that God is our Father would have encouraged him. However, Paul eliminated the possibility of permissiveness implied in "Father" by using "Lord." Timothy needed to remember that the Lord had called him to serve a God who loved him as a father yet deserved complete obedience as his lord. We share Timothy’s need.