How do we know that Christians will have eternal life?

The assurance of eternal life for believers is intricately linked to the doctrine of justification, as articulated in Romans 3:24, which states that we are justified freely by God's grace through the redemption that is in Christ Jesus. This justification is not based on any works or merit of our own, but solely on God's grace and the finished work of Christ. Additionally, Ephesians 1:4-5 emphasizes our election in Christ before the foundation of the world, ensuring that those whom God has chosen will receive eternal life. Thus, the promise of eternal life rests upon the faithfulness of God and the completed work of Christ, which is the foundation of our hope as Reformed Christians.