How do we know the doctrine of union with Christ is true?

The truth of union with Christ is affirmed throughout the New Testament, particularly in Ephesians 2, where it states that we are made alive together with Christ and raised up to sit with Him in heavenly places. This doctrine is not merely theological; it shapes the believer's identity and experience. Romans 8 reinforces this by asserting that there is no condemnation for those who are in Christ Jesus, proving that our salvation and security are irrevocably linked to our union with Him. Thus, the doctrine holds both scriptural affirmation and experiential reality for believers.