How do we know that believers are actually brothers and sisters in Christ?

The designation of believers as brothers and sisters in Christ is rooted in our shared spiritual rebirth and identity in Christ. In Philippians 2:25, Paul refers to Epaphroditus as 'my brother,' indicating that their relationship is grounded in their common faith and the transformative work of the Holy Spirit. The Greek term for 'brother' implies a familial bond, suggesting that all who are born again in Christ are adopted into God's family.

This spiritual kinship emphasizes that believers are valued not based on earthly measures, but rather on their identity as children of God. It is a reminder that regardless of our previous lives, we now share a divine heritage, being heirs of God and co-heirs with Christ. This brotherly love encourages the church body to support one another, pray for each other, and engage in ministry, thus fulfilling the commands laid out by Christ to love one another.