How do we know that believers are born into God's city?

According to Psalm 87, the citizens of God's glorious city are those who have experienced a second birth, one that is spiritual in nature. This is confirmed by the New Testament teaching, where Jesus explains to Nicodemus that to enter the Kingdom of God, one must be born again (John 3:3). This spiritual birth occurs when the Holy Spirit regenerates an individual, enabling them to recognize and trust in Christ as their Savior. The beauty of this doctrine illustrates that God’s grace transforms people originally opposed to Him into citizens of His glorious city, which is a testament to His saving and sovereign grace.