"From the beginning God had revealed Himself to be a personal God, but more amazing is this; when Christ came in the flesh as the great revelation of God, He revealed God to be God in Father and Son." - The Apostolic Revelation, Chapter 9.
God is a Father to a Son, and also a Son to a Father - the nature of God is revealed to us in this dynamic relationship. Why should we be surprised if the Body of Christ were also to have these kinds of fathering and sonship relationships throughout. It does in fact, and the Bible is also full of the examples and language of sonship. Once you notice it, you find it is everywhere as demonstrated here. A search of your own will find even more examples:
"Very truly I tell you, the Son can do nothing by himself; he can do only what he sees his Father doing, because whatever the Father does the Son also does." (John 5:19)
"Father, just as you are in me and I am in you. May they also be in us..." (John 17:20)
"I became your father through the gospel" - Apostle Paul, (1 Corinthians 4:15)
"To bring many sons to glory" (Hebrews 2:10)
"This is my beloved Son, whom I love, with him I am well pleased." (Matt 3:17)
"He will turn the hearts of the fathers to the children, and the hearts of the children to their fathers or else I will come and strike the land with a curse." (Malachi 4:5-6)
"I urge you to imitate me. For this reason I am sending you Timothy, my son whom I love." (1 Corinthians 4:16)
"To Titus, my true son in our common faith" (Titus 1:4)
"You are no longer a slave, but a son" (Galatians 4:7)
"You received the Spirit of Sonship" (Romans 8:15)
Many verses that include the word son are not in reference to being a son/s of God, but also to being son/s of other people who are not biologically related. The concept of sonship in scripture is not only toward God our Father, but also toward other 'fathers' that God placed in the earth for our benefit. It's true that we are brothers of Christ and as such are adopted as sons, but the volume of references that mention sons and 'earthly' fathers in reference to each other shows it something for here and now, and between people too.
So sonship is not only toward God, but toward leaders (fathers) over us in the Lord. A spiritual father is more than just a "godparent." A spiritual father is someone who cares for us, who imparts to us love, identity, spiritual covering, who prays for us, and is concerned for our well being. In return we love, honour, serve, and care. We also give in return to make our spiritual fathers work easy, and receive covering from them, and grace, and the blessing of Christ.
A spiritual father is someone God has placed in our lives for our spiritual well being. We should submit to them, give our hearts and serve and honour them. In return God will bring good to us through them. They are a source of life to us through Christ.
Through this the example of the Father and Son becomes alive and real. God our Father in Heaven had a Son, Jesus Christ, who is also God. So God is a son as well as a Father. And the Body of Christ will have the same function and form as God, we are made in His image. We too will have fathers and sons.
For more detail you will need to read Chapter 9 of "The Apostolic Revelation."