At one time, all of us where aliens, or foreigners to God the Father.
Yet His Son Jesus came and reconciled us to Him:
"But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ." (Ephesians 2: 13)
In fact, Paul calls all of us who believe in Jesus "fellow citizens":
"Now therefore ye are no more strangers and foreigners, but fellowcitizens with the saints, and of the household of God;" (Ephesians 2: 19)
In the next passages, we learn about our citizenship in the Kingdom of Heaven, although rendered "conversation" in the King James Bible:
"Only let your conversation be as it becometh the gospel of Christ: that whether I come and see you, or else be absent, I may hear of your affairs, that ye stand fast in one spirit, with one mind striving together for the faith of the gospel;" (Philippians 1: 27)
"For our conversation is in heaven; from whence also we look for the Saviour, the Lord Jesus Christ:" (Philippians 3: 20)
Today, we are no longer aliens or strangers, but we are citizens in God's Kingdom through His Son Jesus, kings and priests (1 Peter 2: 9) through Jesus, the King of Kings and our High Priest Forever.