In John 14:18, Jesus promised, “I will not leave you as orphans; I will come to you.” This is His promise to be with us as our Father. For if He does not become our Father, then His coming to us still leaves us as orphans.
If a man is visiting a boy in the orphanage and says to the youngster upon leaving, “I will not leave you as an orphan; I will come to you,” the man is not merely promising to visit the boy once again. He’s promising to come and claim the child as His own. He’s promising to adopt the boy.
For more on our adoption as sons, you may want to see what Paul writes about it in Romans 8:15, 23; 9:4; Galatians 4:5; and Ephesians 1:5.
For more on the general subject of Christ being our Father, see: